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## Introduction 

In the ever-evolving construction industry, new materials and techniques are constantly being introduced to meet the demand for sustainable and efficient building solutions. One such material that has gained significant popularity in recent years is cold-formed steel. 

This article serves as a comprehensive guide for structural engineers who are interested in using cold-formed steel as a structural material in residential and light commercial projects. We will explore what cold-formed steel is, its benefits, its applications in building construction, and key considerations for engineers

## What is Cold-Rolled Steel?

Cold-formed steel refers to steel products that are formed by cold-working processes, such as rolling or pressing, at room temperature. 

Unlike hot-rolled steel, which is shaped while it is heated, cold-formed steel is manufactured at lower temperatures, resulting in distinct mechanical properties. 

Cold-formed steel exhibits excellent strength-to-weight ratio, dimensional stability, and uniformity in shape and size. These properties make it an attractive choice for a wide range of applications in the construction industry, and it has become particularly popular as a framing choice in residential builds.

![Cold-Formed Steel Construction from https://www.ispansystems.com/news/cost-comparison-cold-formed-steel-concrete-wood/](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/Cold_Formed_Steel_5526d0d3ce.jpg)
_Figure 1: Example of cold-formed steel in residential & light commercial projects ([Reference](https://www.ispansystems.com/news/cost-comparison-cold-formed-steel-concrete-wood/))_

## Cold-Formed Steel as a Building Material

Cold-formed steel offers numerous benefits as a construction material. 

Firstly, it is highly durable and resistant to corrosion, ensuring long-term structural integrity. 

Secondly, cold-formed steel possesses higher strength, fire resistance, dimensional stability and is lighter than hot rolled steel and timber, allowing for the creation of lightweight structures permitting longer spans without compromising on load-bearing capabilities. 

### Comparison Between Cold-Formed Steel vs. Hot-Rolled Steel

The different manufacturing procedures between cold-formed steel and hot-rolled steel are summarised quite succinctly in[ this video](https://www.youtube.com/watch?v=OBG7Y5_Cf_s) as well as a high-level overview of the key differences between the two steel types in the below comparison.

#### Cold-Formed Steel

- **Manufacturing Process:** Cold-Working
- **Mechanical Properties:** High Strength
- **Corrosion Resistance:** Excellent
- **Dimensional Stability:** High
- **Fire Resistance:** High
- **Design Flexibility:** High
- **Weight:** Lighter
- **Sustainability:** Recyclable
- **Price:** More Expensive
- **US Design Standards:** American Iron and Steel Institute (AISI) S100 - "North American Specification for the Design of Cold-Formed Steel Structural Members."
- **Australian Design Standards:** [AS/NZS 4600 - Cold-formed steel structures.](https://clearcalcs.com/standards/SA/AS-NZS-4600-2018-0)

#### Hot-Rolled Steel

- **Manufacturing Process:** Hot-Working
- **Mechanical Properties:** High Ductility
- **Corrosion Resistance:** Moderate
- **Dimensional Stability:** Moderate
- **Fire Resistance:** Moderate
- **Design Flexibility:** Moderate
- **Weight:** Heavier
- **Sustainability:** Recyclable
- **Price:** Less Expensive
- **US Design Standards:** [American Institute of Steel Construction (AISC) 360 - Specification for Structural Steel Buildings.](https://www.steel.org.au/resources/elibrary/library/ansi-aisc-360-16-specification-for-structural-steel-buildings/)
- **Australian Design Standards:** [AS 4100:2020 - Steel structures](https://clearcalcs.com/standards/SA/AS-4100-2020-0)

## Cold-Formed Steel Framing

One of the primary applications of cold-formed steel in construction is framing. 

### Steel vs. Timber Framing

Cold-formed steel framing offers several advantages over traditional wood framing. It provides enhanced structural stability, as the material's consistent properties and uniformity eliminate common issues such as warping, splitting, or shrinking. 

Moreover, cold-formed steel framing allows for greater design flexibility, facilitating the creation of complex architectural shapes and configurations that aren’t achievable with timber due to its rigid material properties. 

While supply lead times and cost are the most critical factors in determining the choice of framing (which can be considered by contacting local framing suppliers), the below section can help a structural engineer choose between timber and steel framing.

### Timber Framing

#### Advantages of Timber Framing

1.  **Sustainability**: Timber is a renewable resource and has a lower carbon footprint compared to steel. 
2.  **Insulation**: Timber has natural insulating properties, providing better thermal performance and reducing energy consumption.
3.  **Aesthetics**: Timber framing provides a warm and traditional look that many homeowners find appealing. 
4.  **Cost-effectiveness**: Timber framing is often less expensive than steel framing, especially for smaller residential projects which can be stick-built on site.
5.  **Ease of construction**: Timber frames are lightweight and easier to handle, making them more suitable for DIY projects or remote locations.

### Disadvantages of Timber Framing

1. **Vulnerability to pests**: Wood can be susceptible to termite and rot damage if not properly treated and maintained.
2. **Limited span capabilities**: Timber frames may require additional supports or columns for larger open spaces compared to steel frames.
3. **Fire risk**: Wood is combustible, which increases the risk of fire and may require additional fireproofing measures.
4. **Shrinkage and warping**: Wood can expand, shrink, and warp over time, potentially leading to structural issues or cosmetic problems.
5. **Limited load-bearing capacity**: Timber has lower load-bearing capacity compared to steel, restricting design options for larger or more complex structures.

### Steel Framing

#### Advantages of Steel Framing

1. **Strength and durability**: Steel framing offers superior strength, stability, and resistance to weather, pests, and rot.
2. **Design flexibility**: Steel allows for longer spans and greater design freedom, making it suitable for modern architectural styles and large open spaces.
3. **Fire resistance**: Steel is non-combustible and offers better fire resistance, providing added safety and potentially lowering insurance costs.
4. **Minimal maintenance**: Steel frames are not susceptible to pests, rot, or warping, resulting in lower maintenance requirements.
5. **Sustainability (recyclability)**: Steel is highly recyclable and can be reused, reducing environmental impact and waste.

#### Disadvantages of Steel Framing

1. **Higher cost**: Steel framing is generally more expensive than timber framing, particularly for smaller residential projects or projects with more non-standard dimensions.
2. **Conductivity**: Steel is a conductor of heat and electricity, which can affect energy efficiency and require additional insulation measures.
3. **Aesthetics**: Steel frames may lack the warmth and natural appearance of timber, which may not appeal to some homeowners.
4. **Sound transmission**: Steel can transmit sound more effectively than wood, potentially requiring additional soundproofing measures.
5. **Weight and handling**: Steel frames are heavier and require specialized equipment for assembly and transport.

From an environment perspective, steel framing is preferred in certain environments due to its inherent properties and advantages. These include:
- Seismic Zones: Steel framing has excellent ductility and resilience, making it ideal for areas prone to earthquakes. It can absorb and dissipate seismic forces, reducing the risk of structural damage.
- Extreme Weather Conditions: Steel framing is resistant to high winds, hurricanes, and other severe weather conditions. It offers enhanced durability and stability in regions with harsh climates.
- Industrial and Commercial Structures: Steel framing is widely used in industrial and commercial construction due to its versatility, ability to span long distances without intermediate supports, and suitability for large open spaces.

Timber framing, on the other hand, is preferred in different environments due to its unique characteristics and benefits. These include:
- Residential Construction: Timber framing is commonly used in residential buildings, particularly single-family homes and low-rise structures. It provides a warm and natural aesthetic appeal to these spaces.
- Environmental Considerations: Timber framing is a renewable and sustainable building material. It has a lower carbon footprint compared to steel, as trees absorb carbon dioxide during their growth. Timber is preferable in jurisdictions that have carbon taxes or financial incentives for using renewable materials.
- Rural and Remote Areas: Timber framing is often preferred in rural and remote locations due to its availability and ease of transportation. It can be sourced locally, reducing logistical challenges and costs.

## Key Considerations for Structural Engineers

Structural stability and load-bearing capabilities of cold-formed steel are critical factors to consider. 

Cold-formed steel framing products have undergone extensive testing to determine their structural properties and performance. Structural engineers should consult manufacturer specifications and relevant design standards to ensure proper design and selection of cold-formed steel components.

The typical failure modes for cold formed steel framing include:
- **Buckling**: Cold-formed steel members are slender and susceptible to buckling under compressive loads. Engineers need to carefully analyze and design the framing system to prevent buckling failures, especially in columns and walls subjected to axial compression.
- **Lateral-Torsional Buckling**: Cold-formed steel beams and joists can experience lateral-torsional buckling, which occurs when the member twists and deflects laterally under combined bending and torsion. Engineers must evaluate the member's resistance to lateral-torsional buckling and employ appropriate bracing or design provisions to prevent failure.
- **Connection Failure**: Adequate connection design is crucial for the structural performance of cold-formed steel framing. Insufficiently designed or poorly executed connections can lead to local failures, compromising the overall stability and load transfer within the framing system.
- **Shear and Web Crippling**: Cold-formed steel members, such as studs and joists, can fail in shear or experience web crippling. Shear failures occur when the applied load exceeds the shear capacity of the member. Web crippling occurs when the flanges of a member buckle or deform due to concentrated loads from bearing elements or fasteners.
- **Material Yielding and Plastic Deformation**: Cold-formed steel can undergo yielding and plastic deformation under high loads. Engineers must carefully analyze and design members to ensure they remain within acceptable stress limits to avoid excessive deformation or failure.
- **Corrosion**: While cold-formed steel is more resistant to corrosion compared to hot-rolled steel, it is still susceptible to corrosion when exposed to moisture or corrosive environments. Corrosion can weaken the steel members and compromise their structural integrity.
- **Construction Tolerances**: Cold-formed steel framing requires precise fabrication and installation to maintain the intended design and structural performance. Deviations from design tolerances during manufacturing or construction can affect the overall stability and strength of the framing system.

The use of appropriate design software is crucial for the accurate analysis and design of cold-formed steel members. Specialized software packages, such as [ClearCalcs Calculations](https://clearcalcs.com/calculations), are compliant with the AISI (American Iron and Steel Institute) or AS/NZS (Australian and New Zealand Standards) design codes, and provide efficient tools for engineers to optimize their designs.

Before using design software, it is essential to familiarize oneself with the relevant building codes and regulations in the United States and Australia. 

Cold-formed steel design standards, such as AISI S100 in the United States and AS/NZS 4600 in Australia, provide guidelines for the safe and efficient use of cold-formed steel in construction. 

ClearCalcs has these standards built into the cold formed steel design software and can design a range of cold-formed steel structural components, including:
- [Cold-Formed Steel Beam (AS 4600:2018) - Joists, Rafters, Bearers, etc. to Australian Standards](https://clearcalcs.com/calculations/cfsSteelBeamAS4600-2018)
- [Cold-Formed Steel Column (AS 4600:2018) - Studs or Isolated Compression Members to Australian Standards](https://clearcalcs.com/calculations/cfsSteelColumnAU)
- [Cold-Formed Steel Design-Only Member (AS 4600:2018) - Design Using External FEA Results to Australian Standards](https://clearcalcs.com/calculations/cfsSteelMemberAS4600-2018)
- [Cold-Formed Steel Beam (AISI S100-16) - Joists, Rafters, Girders, etc to US Standards](https://clearcalcs.com/calculations/cfsSteelBeamAISI)
- [Cold-Formed Steel Column (AISI S100-16) - Studs or Isolated Compression Members to US Standards](https://clearcalcs.com/calculations/cfsSteelColumnAISI)

## Cold-Formed Steel Manufacturers

For structural engineers considering the use of cold-formed steel, it is essential to work with reputable manufacturers who produce high-quality products. 

In the United States, some well-known cold-formed steel manufacturers include BlueScope, Simpson Strong-Tie, and Clark Dietrich. These manufacturers adhere to stringent quality control measures and often have certifications, such as ISO 9001, which ensure their commitment to delivering reliable and consistent products. 

The below section summarises the main cold-formed steel manufacturers in Australia & the US.

### [BlueScope Steel](http://www.bluescopesteel.com.au/)
**Location:** US & Australia

**Certifications:** BlueScope Steel holds certifications such as ISO 9001 for quality management systems, ISO 14001 for environmental management systems, and AS/NZS 4801 for occupational health and safety management systems.

**Quality Control Measures:** BlueScope Steel maintains strict quality control measures throughout their manufacturing process, including material testing, adherence to Australian standards, and regular inspections to ensure high product quality and performance.

### [Lysaght](https://www.lysaght.com/)

Location: Australia

**Certifications:** Lysaght is certified with ISO 9001 for quality management systems and AS/NZS 4801 for occupational health and safety management systems.

**Quality Control Measures:** Lysaght upholds stringent quality control standards through comprehensive material testing, compliance with Australian standards, and continuous improvement initiatives. They also work with a network of authorized fabricators who undergo training and audits to ensure product quality.

### [ClarkDietrich Building Systems](https://www.clarkdietrich.com/)

**Location:** US

**Certifications:** ClarkDietrich holds certifications such as ISO 9001 for quality management systems, ISO 14001 for environmental management systems, and OSHA's SHARP (Safety and Health Achievement Recognition Program) certification.

_Quality Control Measures:_ ClarkDietrich implements comprehensive quality control measures, including rigorous material testing, in-process inspections, and compliance with industry standards like ASTM. They have a robust quality management system in place to monitor and maintain consistent product quality.

### [Simpson Strong-Tie](https://www.strongtie.com/)

**Location:** US

**Certifications:** Simpson Strong-Tie is certified with ISO 9001 for quality management systems and ISO 14001 for environmental management systems.

**Quality Control Measures:** Simpson Strong-Tie follows stringent quality control measures throughout their manufacturing process. This includes rigorous material testing, adherence to industry standards, and continuous product monitoring to ensure high-quality cold-formed steel components.

### [Steel Dynamics, Inc](https://stld.steeldynamics.com/)

**Location:** US

**Certifications:** Steel Dynamics, Inc. maintains certifications such as ISO 9001 for quality management systems and ISO 14001 for environmental management systems.

**Quality Control Measures:** Steel Dynamics implements rigorous quality control measures at every stage of their manufacturing process. This includes material testing, quality inspections, and compliance with relevant ASTM standards to guarantee product performance and reliability.

In Australia, although cold-formed steel is not standardized, structural engineers can refer to local manufacturers who specialize in cold-formed steel products. 

Collaborating with experienced manufacturers is vital to ensure access to reliable technical support, accurate product information, and compliance with local regulations. It's important to note that certifications and quality control measures may evolve over time, and it's advisable to visit the manufacturers' websites or contact them directly for the most up-to-date information regarding their certifications and quality control processes.

## Conclusion

Cold-formed steel is an increasingly popular choice for structural engineers in residential and light commercial projects. Its unique properties, including durability, strength, and resistance to fire and pests, make it an attractive alternative to traditional construction materials. Cold-formed steel framing offers advantages over wood framing, such as increased structural stability and design flexibility.

When using cold-formed steel, structural engineers must consider key factors such as design software, building codes, and manufacturer specifications. Utilizing specialized design software ensures accurate analysis and optimization of cold-formed steel members. Compliance with building codes, such as AISI S100 in the United States and AS/NZS 4600 in Australia, ensures the safety and quality of the project.

Choosing reputable cold-formed steel manufacturers is crucial for obtaining high-quality products. In the United States, manufacturers such as BlueScope, Simpson Strong-Tie, and Clark Dietrich are known for their commitment to quality and adherence to industry standards. In Australia, working with local manufacturers who specialize in cold-formed steel products ensures access to reliable technical support and compliance with local regulations.

In comparison to timber, cold-formed steel offers numerous benefits as a construction material. Its durability, strength, and resistance to fire and pests make it an ideal choice for residential and light commercial projects. By embracing this innovative material which can be easily designed for using ClearCalcs Calculations, engineers can achieve efficient and sustainable structures that meet the demands of the modern construction industry.

Structural engineers are encouraged to explore the possibilities of cold-formed steel for their next project. By embracing this innovative material, they can benefit from its superior properties, design flexibility, and sustainable attributes of CFS. As the construction industry continues to evolve, cold-formed steel offers a promising solution in the search for lightweight higher strength, corrosion & fire-resistant materials.



This article serves as a comprehensive guide for structural engineers who are interested in using cold-formed steel as a structural material in residential and light commercial projects. We will explore what cold-formed steel is, its benefits, its applications in building construction, and key considerations for engineers.

Cold-Formed Steel: A Guide for Residential and Light Commercial Projects

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## 1. What is Creep Deflection in Structural Wood?

Wood is a viscoelastic material, exhibiting both viscous and elastic characteristics when undergoing deformation. As a result, it suffers from creep behavior under long-term loading. Creep is the permanent sag caused by the stretching and adjusting of the wood fibers to the long-term loads on them, such as the weight of the member itself, the deck it supports, and other building components. It is a time-dependent deformation from constant stress that develops over years, and accelerates with frequent and drastic temperature and moisture content changes. Creep is an important factor to consider in the design and durability of timber structures. 

## 2. IBC 2018 Deflection Limits (1604.3)

Structural components must have enough stiffness to limit the deflections indicated in the IBC. For instance, members supporting brittle finishes (e.g. plaster walls) are limited to a lower allowable deflection, while members with flexible finishes are allowed a much higher allowable deflection limit. For D+L deflection, the incremental deflection is calculated and compared to the deflection limits. This includes the effects of creep but excludes instantaneous dead-load deflection, which takes place during construction and before deflection-sensitive elements are installed (e.g. glazing, masonry walls, marble flooring). For this reason, members subjected to D+L loads are allowed a larger deflection limit than those subjected to S,W,L, or Lr loads. 

## 3. Creep Deflection Calculation in IBC 2018 (1604.3)

The deflection limit for the D+(L+Lr) load combination only applies to the deflection due to the creep component of long-term dead load deflection plus the short-term live load deflection. For wood used under dry conditions, creep deflection is estimated as half of the immediate dead load deflection. When used at all other moisture conditions, it is estimated to be the same as the immediate dead load deflection. 

You can design wood beams and calculate deflection with [ClearCalcs Wood Beam Calculator here](https://clearcalcs.com/calculations/us/timberBeamASD).

## 4. Creep Deflection Calculation in NDS 2018 (3.5.2)

The total deflection of a member is calculated as the sum of the deflection due to short term load and the immediate deflection due to long-term load, where the latter is multiplied by a time dependent factor. As mentioned above, creep is a time-dependent deformation that accelerates with frequent and drastic temperature and moisture content changes. As such, the immediate deflection due to long-term load is increased by half for dry wood, and doubled for glue laminated timber and wet wood. Since deflection limits are typically set by the IBC, which considers only the creep component of deflection, the NDS formula results in the same deflection calculation as the IBC. 


Understand Creep Deflection Calculation in Structural Design | Learn about creep deflection and its impact on structural elements. Discover how to account for creep deflection in your design calculations to ensure long-term stability and performance.

Creep Deflection in Structural Wood Beam Design

Deform bar steel bars used in concrete footings 

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Deform bar steel bars used in concrete footings

## What is Development Length?

Steel reinforcement (rebar) in concrete footings generally acts in tension to resist bending loads that arise as the footing spreads loads uniformly over the soil underneath. However, those tension loads have to be transmitted between the concrete (where the load is applied) and the rebar. For this to happen, there has to be enough "grip" between the concrete and the rebar - otherwise the rebar would just get ripped right out of the concrete! Because rebar breaking out of concrete is generally an undesirable scenario (think a sudden bang with no warning), engineers generally ensure that there's enough grip between concrete and rebar to ensure that the rebar reaches its full yield strength. That lets us use the full strength of the steel for greater efficiency, and is accompanied by large movements that'll give plenty of warning to occupants. 

The length of rebar required to achieve the necessary grip is what we call the development length. Since the rebar can be considered "ineffective" over its development length, it's desirable to minimize this length as much as possible. The most common way to reduce this length is to add ribs to the rebar, which grip the concrete around them. Another solution often employed is to "hook" bars by bending the ends 90 degrees, which significantly reduces the required development length at the expense of having to bend rebar and fitting the "hooks". Note that the bigger the bar, the longer the development length required, as they can take more force!

## Code Requirements for Development Length

As previously described, it's generally very desirable to "fully develop" bars, which means providing enough development length that the rebar can reach its full yield strength before ripping out the concrete. This is also reflected in building codes, which will almost always require that rebar be fully developed. For instance, ACI 318-19, the concrete design standard principally used in the USA, provides equations for development length that directly depend on the yield strength of the rebar. The equation below is taken directly from ACI 318-19, as implemented in ClearCalcs.

![ACI 318-19 Development Length Equation](https://clearcalcs-prod2-cms.s3.amazonaws.com/ACI_318_19_Development_Length_Equation_42ad0645fa.png)

Providing this development length is an  essential part of reinforced concrete design. Formulas and methods used to analyze the strength of concrete members are practically all dependent on the assumption that the rebar can reach its full yield strength. Thus, not providing enough development length can very much lead to premature failures.

However, to account for the fact that it may be impractical to reach full development lengths in some situations (the largest bars can require over 10 feet of development length!), the code also allows reducing the development length, in some cases, as a proportion of the required steel vs what is provided. So if far more steel is provided than is required, the development length may be reduced - but only down to a hard limit of 12 inches, and it can't apply to reinforcement provided for things like increased ductility or when resisting seismic loads.

## Development Length in Footings

When calculating the rebar required in footings, we look at a critical section for bending moment, generated by the action of load being spread uniformly from the column to the entire area of the footing. As you can see on the image below, the available length for development of the rebar is the distance between the column face and the footing edge, less the concrete cover.

![Development Length in Footings](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/Development_Length_in_Footings_58821df030.png)

In larger footings such as used in commercial buildings, it's generally never an issue to achieve development of the rebar. However, in smaller footings such as in residential construction, this can be a problem. Even when using small bar sizes and applying all the reductions allowed by the ACI 318-19 code, we're still left with the 12" hard limit on development length, which, if combined with 3" cover and assuming a 6"x6" post, means we need a footing at least 3 feet wide. This may often be larger than typical construction practices, which have been proven time and time again to be sufficient. So how do we accommodate this? Let's look at one solution...

## Plain Concrete - No Development Required!

If we don't want to deal with rebar development length, there's one simple solution: skip the rebar! Indeed, the ACI code specifically allows concrete footings to be designed without any rebar, using the small tensile capacity of concrete to resist the bending loads we discussed previously. In reality, this winds up being more of an "arch" action, where load gets spread in compression diagonally into the soil below. When using these provisions, there's nothing saying we can't actually still include rebar in there - just that we can't consider it to strengthen the footing.

Specifically with small residential footings where loads are small and the footings relatively "stubby", it's almost always the case that footings will be adequate when considering only the plain concrete. So if you've had the same typical detail for small footings calling out a small grid of #5 rebars for the last two decades and were surprised to find that it wasn't passing due to development length, fear not! The best way to handle this in ClearCalcs is to design as Plain Concrete, and simply to specify your desired rebar pattern in your drawings afterwards. 

Try [ClearCalcs Spread Footing (ACI 318-14) Calculator](https://clearcalcs.com/calculations/us/foundationsSpreadFootingUSA) now!

![Plain Concrete selection in ClearCalcs Concrete Footing Calculator](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/Plain_Concrete_selection_in_Clear_Calcs_Concrete_Footing_Calculator_9b788ef148.png)

Development Length in Footings Explained | Learn about the importance of development length in reinforced concrete footings. Understand the code requirements, factors affecting development length, and solutions to accommodate it in your footing design for safe and efficient construction.

Development Length in Reinforced Concrete Footings

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Concrete Foundation of a House

A number of significant updates have been made with [AS3600:2018 Amdt 2](https://clearcalcs.com/standards/SA/AS-3600-2018-0), whose key effects are on the spacing and quantity of shear fitments / ligatures required.

## Capacity Reduction Factor (Bending Moment with compression)

1. Table 2.2.2 (d) has changed the Φ0 factor to be equivalent to 0.65 × kΦ. There is a minor impact on the reduction factor where columns are slender or where Q/G <= 0.25, refer to calculations for kΦ.

## Shear Strength

2. Upper limit shear strength (Vumax) has been reduced by 10% in equation 8.2.3.3(1)

3. Factor kv (simplified method) increases the concrete shear capacity (Vuc) by up to 50% from Amendment 1, in particular for thinner depth sections without reinforcement. Previously a limit of kv = 0.10 was placed for any beam where minimum shear reinforcement was not satisfied or no fitments were provided. This has now been increased to kv = 0.15. Refer Cl 8.2.4.3(a)
 
You can access [AS3600-2018 and other Australian Standards in ClearCalcs here](https://clearcalcs.com/standards/SA/AS-3600-2018-0).

## Fitment Detailing / Spacing requirements

4. The minimum reinforcement spacing is now relaxed for beams with low shear force. Where V* <= ΦVu,min, the fitments may now be spaced at 500mm or 0.75 × D, whereas previously 300mm or 0.5 × D limit was imposed under all circumstances apart from very large beams.
 
5. For a short column satisfying, L < 5 × depth, Amendment 2 has introduced minor changes to the max allowable fitment spacing to reflect the actual fitment strength. spacing = √(fsyf/500) × 24×d instead of spacing = 24×d previously in accordance with Cl 14.5.4(b)
 
6. For beams of depth > 300mm, shear fitments are now required even when V* does not exceed ΦVuc. An additional factor ks has been added factoring down the upper limit shear force that may be taken without adding fitments in Eq Cl 8.2.1.6(1).  

## Renaming of Variables

7. Dc now renamed to b (smaller column cross-sectional dimensions). Refer Cl 1.7.

8. Ks now renamed to ks (Beam Depth Factor to Determine Reinforcement Required). The definition of Ks in Cl 1.7 has not been updated in Amendment 2 from its previous version. It is believed that this definition should be further expanded in future revisions to reflect its use in Cl 8.2.1.6(1).

## Assumptions

The above is not a comprehensive list of Amendment 2 changes. However, they do reflect all the changes that are relevant to calculations performed in ClearCalcs.
ClearCalcs concrete calculators utilise the Simplified Method for calculating kv and θv in compliance with Cl 8.2.4.1. Therefore the Amendment 2 updates for the "General Method" Cl 8.2.4.2 are not listed above.

## ClearCalcs Calculators Affected by Changes

ClearCalcs has updated its calculator for consistency with this new amendment. ClearCalc's concrete calculators affected by Amendment 2 changes are:

- [L-Type Cantilever Retaining Wall ](https://clearcalcs.com/calculations/au/LTypeCantileverRetainingWallAU)
-[ Rectangular Concrete Beam](https://clearcalcs.com/calculations/au/concreteBeamRectangular)
- [Rectangular Concrete Column](https://clearcalcs.com/calculations/au/concreteColumn)
- [Concrete Pad Footing](https://clearcalcs.com/calculations/au/concretePadFooting)
- One-Way Concrete Flat Slab
- [Concrete Wall Footing](https://clearcalcs.com/calculations/au/concreteWallFooting)


Understanding Changes in AS3600-2018 Amendment 2 Concrete | Stay up-to-date with the latest updates to the AS3600-2018 Amendment 2 concrete design standard. Explore the key revisions, additions, and implications for concrete design and construction in Australia. Enhance your knowledge and ensure compliance with the updated guidelines.

Changes in AS3600:2018 Amendment 2 (Concrete)

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Sleeper Retaining Wall.jpg

Sleeper retaining walls are a common type of earth retaining structure used in construction projects, and they are designed to retain soil and prevent erosion. In accordance with the Australian Standards AS4678-2002 Earth Retaining Structures, the design of sleeper retaining walls must take into account the soil conditions of both the backfill and footing soil. This ensures that the wall is designed to withstand the loads and forces that it will be subjected to over its service life.

The different types of soil conditions specified in AS4678-2002 provide different levels of uncertainty, and these are taken into account when calculating the soil properties for the design. Table 5.1 in the standard applies uncertainty factors to the soil properties specified, depending on the soil condition.

The first type of soil condition is **Controlled Fill Class I**, which pertains to soil, rock or other inert material that has been placed on site in a controlled fashion such that the average compacted density is 98% (no less than 95%) of the maximum dry density when tested in accordance with AS1289.5.1.1. This type of soil is considered to have a low level of uncertainty, and it is typically used in engineered fill applications where the soil has been placed and compacted to a high level of density.

The second type of soil condition is **Controlled Fill Class II**, which pertains to soil, rock or other inert material that has been placed on site in a controlled fashion such that the average compacted density is 95% (no less than 92%) of the maximum dry density when tested in accordance with AS1289.5.1.1. This type of soil is also considered to have a low level of uncertainty, but it is typically used in less critical applications where the soil has been placed and compacted to a slightly lower level of density.

The third type of soil condition is **Uncontrolled Fill**, which pertains to soil, rock or other inert material that has been placed on site without the compaction density as defined for either control fill. This type of soil is considered to have a higher level of uncertainty, as it has not been placed and compacted in a controlled fashion. Uncontrolled fill is typically used in less critical applications where the soil properties are less important.

The fourth and final type of soil condition is **In-situ Material**, which pertains to natural soil found on site. This type of soil is considered to have the highest level of uncertainty, as the properties of the soil are not well understood and can vary widely.

When designing a sleeper retaining wall, the soil conditions must be taken into account in both the backfill and the footing soil. The soil properties must be calculated based on the uncertainty factors specified in AS4678-2002, and the design must be based on the worst-case scenario for the soil conditions. This ensures that the wall is designed to withstand the loads and forces that it will be subjected to over its service life. 

[(Try ClearCalcs Sleeper Retaining Wall Calculator to AS 4678:2002 now for free)](https://clearcalcs.com/calculations/au/retainingWallSleeperCohesive)

In conclusion, the soil conditions are a critical factor in the design of sleeper retaining walls, and they must be taken into account in accordance with the Australian Standards AS4678-2002 Earth Retaining Structures. The different types of soil conditions specified in the standard provide different levels of uncertainty, and these are applied to the soil properties specified in the design. By taking into account the soil conditions, engineers can ensure that the sleeper retaining wall is designed to withstand the loads and forces that it will be subjected to over its service life, and provide a safe and durable structure.

Soil Conditions in Sleeper Retaining Wall Design according to Australian Standards AS4678-2002 | Learn about the importance of soil conditions in the design of sleeper retaining walls. Explore key factors such as soil types, properties, and their impact on wall stability.

Soil Conditions in Sleeper Retaining Wall Design according to AS4678-2002

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Structural design is an essential aspect of building construction, and it involves the application of engineering principles to ensure that structures can withstand the loads and forces they will be subjected to throughout their service life. Two methods of structural design are commonly used in the United States: Allowable Stress Design (ASD) and Load and Resistance Factor Design (LRFD). Both methods have their pros and cons, and the choice between them depends on several factors, including the type of material being used, the complexity of the structure, and the design philosophy of the engineer.

At a high level, ASD checks service load stresses against an allowable stress, whereas LRFD uses factored load forces against a maximum strength LRFD. ASD is the more traditional method and has been in use for many years. It is based on the concept that the stress in a structural member should not exceed a certain level, known as the allowable stress. This allowable stress is determined based on the properties of the material being used, such as its strength and stiffness, and the safety factor required to ensure that the structure can withstand unforeseen loads and environmental conditions. The allowable stress is calculated based on several factors, including the type of loading, the duration of the load, and the type of material being used.

LRFD, on the other hand, is a newer and more modern method of structural design. It is based on the concept that structures should be designed to withstand loads that are expected to occur with a certain probability, rather than just designing for the maximum loads that could occur. LRFD uses factored load forces, which are obtained by multiplying the service loads by load factors, to calculate the maximum strength of a structural member. The load factors are based on the probability of the loads occurring, and they are intended to account for uncertainties in the loads and the strength of the materials being used.

One of the advantages of LRFD is that it can result in more efficient and cost-effective designs. By designing for loads that are expected to occur with a certain probability, rather than just designing for the maximum loads, engineers can reduce the size and amount of materials required for a structure. This can result in cost savings and reduce the environmental impact of the construction project. ([Try ClearCalcs Steel Beam Calculator to AISC 360-16 (LRFD)](https://clearcalcs.com/calculations/us/steelBeamAISC))

However, many engineers still prefer to design using ASD, particularly when designing structures made from wood. This is because wood is a natural and variable material, and it is difficult to accurately predict its strength and stiffness. ASD allows engineers to account for this variability by using conservative values for the allowable stress. This means that the resulting designs are more robust and less likely to fail due to unexpected variations in the material properties. ([Check out ClearCalcs Wood Beam (ASD) Calculator to NDS 2018 here](https://clearcalcs.com/calculations/us/timberBeamASD))

Another advantage of ASD is that it is a simpler method of design, and it is easier to understand and implement than LRFD. This can be particularly important for small-scale construction projects or for engineers who are not familiar with the more complex LRFD method.

In conclusion, both ASD and LRFD are valid methods of structural design, and the choice between them depends on several factors, including the type of material being used, the complexity of the structure, and the design philosophy of the engineer. While LRFD is the newer and more modern method, many engineers still prefer to design in ASD, particularly in wood. Ultimately, the goal of any structural design is to ensure that the structure is safe, durable, and cost-effective, and both methods of design can achieve this goal when used appropriately.


ASD and LRFD Calculations | Understand the difference between Allowable Stress Design (ASD) and Load and Resistance Factor Design (LRFD) methods in structural engineering calculations. 

ASD vs LRFD calculations in Structural Design

An image showing how Australian Standards are available and integrated in ClearCalcs structural engineering design and analysis platform

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As of today, the Australian Standards which are primary references in [the National Construction Code](https://ncc.abcb.gov.au/), can be accessed and referenced in real time in the ClearCalcs’ platform alongside its comprehensive calculation tools. It is the first time that these guidelines for the construction and engineering industry have been available in a digitally integrated format.

As the leading independent software platform for engineers looking to check and streamline their calculation needs, ClearCalcs approached [Standards Australia](https://www.standards.org.au/) knowing that together, they could enable the industry to build more compliant and creative structures. 

The partnership was designed to not only promote stronger adoption of industry best practice, but to encourage engineers to more safely and confidently explore new ideas and concepts.

Launched in 2017 by co-founders Chris Borzillo and Steven Robinson, ClearCalcs is a fast growing Australian startup with an established presence locally and in the US, Canada, Europe, and New Zealand. 

![An image showing ClearCalcs team based in Toronto](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/Toron_Team_Selection1_82ca3b4d0d.jpg)
![An image showing ClearCalcs team based in Melbourne](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/Team_Selection2_1_ccaceeb8f9.jpg)
_Figure 1: Headed up by co-founders Chris Borzillo, CEO, and Steven Robinson, CTO, ClearCalcs team based in Melbourne and Toronto are revolutionizing workflows across engineering construction sector._

The platform houses a comprehensive library of purpose-built calculator tools that enable [engineers](https://clearcalcs.com/persona/structural-engineer), [architects](https://clearcalcs.com/persona/architect) and [building designers](https://clearcalcs.com/persona/building-designer) to better determine the structural requirements for their projects. 

Speaking of the news, Borzillo said, “Integrating Standard Australia’s guidelines into our platform has been a goal of ours since day one. Our calculators are designed to help engineers make confident decisions faster, and we know that they refer to Australian Standards constantly through this process, which makes marrying the two an absolute no-brainer. 

![ClearCalcs platform showing library of Australian Standards now readily available for engineers to refer to](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/Standards_Library_5ad40f21b8.png)
![An image showing how Australian Standards are available and integrated in ClearCalcs structural engineering design and analysis platform](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/Standards_in_Web_Viewer_7e80a37e63.png)
_Figure 2: ClearCalcs now includes access to the Australian Standards which are primary references in the NCC (National Construction Code)_

“Feedback so far has been phenomenal, especially from senior engineers who keep commenting on its potential to swiftly educate juniors. With our tools, engineers are able to quickly calculate their specific and comprehensive engineering needs, reducing the time it takes for projects to move from concept to reality. With Australian Standards now a core part of our functionality, the credibility and value of our service will only grow. 

“The Standards Australia and ClearCalcs partnership empowers our users to make informed decisions in real-time online, so that they can achieve more with confidence by placing Australian Standards directly alongside the engineer's daily workflow. Together, we are transforming how the engineering industry operates through easy to use, innovation-led distribution of information.

“One of the things that engineers love about working with us is that we enable them to trial new and different materials and solutions that would have previously been too time consuming or costly to consider. Access to up-to-date Australian Standards plays a vital role in giving engineers the confidence to adopt new methods and materials, so in making standards even easier to access and understand, we hope this new partnership will inspire and encourage our clients to lead others in industry to also think outside the box. 

![Australian Standards now available directly in ClearCalcs' library of calculators](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/Standards_Reference_In_App_62eede1329.png)
_Figure 3: Users can directy access relevant clauses and references from within every ClearCalcs calculator with a simple click of a button - no more searching through PDFs to find relevant clauses and formula!_

“In a world where housing supply is at crisis point and the need for sustainable construction methods only continues to rise, we take pride in playing a part in helping our clients improve the design of tens of thousands of homes and structures, and are committed to continuing to push innovation we believe can assist with these challenges.”

Daniel Chidgey, Standards Australia’s Head of Commercial Partnerships said, “We are delighted to partner with ClearCalcs to integrate trusted standards information into their innovative software platform, helping engineers make quality decisions with confidence.

“Engineers typically make hundreds of calculations in engineering projects, often using spreadsheets, clunky platforms, and manual calculations. Mistakes when making calculations can lead to extended project timeframes and costly reworks, so they must be done right from the start. Having Standards Australia’s content embedded into ClearCalc’s intuitive engineering platform has great potential to improve their efficiency and accuracy.

“Together, we are transforming how the Australian engineering industry works with standards. It’s been a pleasure partnering with ClearCalcs to bring engineering standards into the digital world.”

As Australia’s leading independent standards organisation, Standards Australia develops and updates the nation’s standards across multiple industries, including construction and engineering. The ClearCalcs platform rollout has been in beta testing since January. [Find out more here](https://get.clearcalcs.com/standards/).

**For more information:**
Clementine Crowther, Loam Partners, +61 414 490 092, clementine@loampartners.com  

**More about ClearCalcs**
Australian owned, engineering software startup ClearCalcs is creating the world's single source of truth for engineering design calculations. The eng-tech software enables engineers and architects to streamline their calculations across a single platform, from the roof to a building’s foundations, providing unparalleled insight and accuracy to the engineering process. 

**About Standards Australia**
Standards Australia is an independent, not for profit organisation, and Australia’s peak non-government standards development organisation. The work of Standards Australia and its contributors from industry, government and the consumer sector enhances the nation's economic efficiency, international competitiveness and contributes to a safe and sustainable environment for all Australians. Standards Australia’s vision is to be a global leader in trusted solutions that improve life – today and tomorrow: www.standards.org.au

Australian engineering and structural design software, ClearCalcs, has launched an industry-first partnership with Standards Australia. 

ClearCalcs Engineers Industry-First Partnership  with Standards Australia

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This article gives a general overview of the National Construction Code, its importance, and how it affects the workflow of structural designers for residential and light commercial buildings in Australia.

National Construction Code 2022: What You Need to Know

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A solid foundation is the backbone of any residential or commercial structure. The foundation is a crucial component of the building, ensuring the structure remains stable and safe. 

Different types of building foundations have unique features, benefits, and limitations that must be considered while designing a building. 

This article will discuss the different types of foundations used in residential buildings, their applications, pros, and cons.

## Shallow Foundations vs. Deep Foundations

**Shallow foundations** are typically used when the soil is strong enough to support the weight of the building. Shallow foundations usually sit on top of the soil, and they are not buried too deep. These types of foundations are commonly used for residential buildings, light commercial buildings, and smaller structures.

In contrast, **deep foundations** (usually piles) are used when the soil is weak or unstable, and the building's weight needs to be supported by deeper, stronger soils or rocks. Deep foundations can be costly and are usually used for larger and more complex structures, such as skyscrapers, bridges, and large commercial buildings.

## Common Types of Foundations in Residential Structures

### Concrete Slab Foundations

A concrete slab foundation (also known as slab on ground) is a type of foundation that consists of a single layer of reinforced concrete poured directly on top of the soil. 

It is suitable for buildings on level ground or with minimal slope and is commonly used for smaller, lighter structures such as single-family homes, units, or townhouses.

The design of a concrete slab foundation involves calculating the load of the building and the soil-bearing capacity to determine the thickness and strength of the slab. Slabs on ground are often designed to have additional concrete cover to prevent moisture ingress from reaching the reinforcement and degrading the integrity of the foundation. The soil is then leveled and compacted, and a layer of crushed stone or gravel is laid on top to help with drainage. A layer of plastic sheeting is then placed on top of the stone to prevent moisture from seeping into the slab. The concrete is then poured on top of the plastic sheeting and reinforced with steel bars or mesh to increase its strength and durability.

![Concrete Slab on Ground Diagram](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_foundation_types_concrete_slab_36ce7e6e0e.png)
_Figure 1: Concrete slab on ground ([Reference](https://www.researchgate.net/figure/Construction-detail-of-the-concrete-slab-on-ground-floored-case-study-house-depicting_fig5_275954276))_

The benefits of concrete slab foundations include their simplicity of design, ease of construction, and cost-effectiveness for smaller, lighter structures. However, they do not have sufficient capacity for commercial buildings and there is potential for cracking and settling if the soil is not properly compacted, and their lack of access to plumbing and electrical systems, given the building services are cast into or beneath the slab.

Concrete slab foundations are one of the most cost-effective and easy to construct but may not be suitable for larger, heavier structures and can be susceptible to cracking and settling if the soil below the slab differentially settles due to not being properly compacted. Unlike spread footings, concrete slab foundations are not suitable for homes built in areas with unstable soil.

![Construction of a Slab on Ground Foundation](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_foundation_types_concrete_slab_example_0d55784d1f.jpg)
_Figure 2: Construction of a slab on ground foundation ([Reference](https://theconstructor.org/structural-engg/slab-on-ground-construction-design/17421/))_

### Raft Foundation (Mat Foundation)

A raft foundation, also known as a mat foundation, is a continuous slab that spans the entire footprint of a building. 

It is suitable for buildings constructed on unstable soil or with high water tables. This type of foundation is designed to distribute the weight of the building evenly across the soil, providing a stable platform for the structure. 

Raft foundations have internal and edge beams that are thickened sections to support vertical loads like columns or load-bearing walls. In commercial buildings, these thickened sections are changed to deeper piles.

![Raft Foundation Diagram](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_foundation_types_raft_68283929e9.png)
_Figure 3: Raft foundation diagram ([Reference](https://ncc.abcb.gov.au/editions/2019/ncc-2019-volume-two/part-32-footings-and-slabs/part-325-footing-and-slab-construction))_

The design of a raft foundation involves calculating the load of the building and the soil-bearing capacity to determine the thickness of the slab. A reinforced concrete slab is then poured on top of a layer of crushed stone or gravel, which helps to improve drainage and prevent moisture from seeping into the building.

The benefits of raft foundations include their ability to provide a stable base for buildings even on weak soils, their ease of construction, and their cost-effectiveness compared to other foundation types. However, limitations include the need for a careful soil analysis to ensure the foundation can adequately support the weight of the building, and there is the potential for cracking and settling due to soil movement.

![Raft Foundation Construction](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_foundation_types_raft_example_eed5355b0e.jpg)
_Figure 4: Raft foundation construction ([Reference](https://cornellengineers.com.au/what-is-a-raft-slab/))_

Raft foundations are suitable for poor soil conditions and can distribute loads evenly but may be susceptible to uplift and difficulty accessing plumbing and electrical systems, which are often cast into or below the raft in conduits. Raft foundations distribute loads evenly across the entire foundation, making them suitable for larger residential buildings. Raft foundations require more excavation and concrete than spread footings.

### Spread Footing

A spread footing is a type of foundation that spreads the weight of the building across a wider area of soil that can be isolated (several separate footings) or continuous (a single-footing row). 

This type of foundation is suitable for smaller, lighter structures such as single-family homes and smaller apartment buildings.
Like the raft foundation, the design of a spread footing involves calculating the load of the building and the soil-bearing capacity to determine the size and depth of the footing. The footing is then excavated to the appropriate depth, reinforcement is formed, and a concrete base is poured into the excavation.

![Types of Spread Footings](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_foundation_types_spread_footing_07086c6430.png)
_Figure 5: Types of spread footings ([Reference](https://www.youtube.com/watch?v=Gqn4KAHSOgk))_

The benefits of spread footings include their simplicity of design, ease of construction, and cost-effectiveness for smaller, lighter structures. 

However, limitations include their insufficient capacity for larger buildings and their potential for settling and cracking if the soil is not properly compacted. Spread footings are generally the most cost-effective option and are suitable for most soil types. Spread footings are typically the easiest footing to repair or replace.

![Reinforcement Detailing for a Spread Footing](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_foundation_types_spread_footing_example_9af4c47ea1.jpg)
_Figure 6: Reinforcement detailing for a spread footing ([Reference](Reinforcement Detailing for a Spread Footing))_

### Pier Foundations

A pier foundation is a type of foundation system that consists of a series of columns known as piers, which are typically made of concrete or steel, and are installed deep into the ground to support the weight of a building or structure. Each pier is placed at strategic locations under the load-bearing walls or columns of the building, and the weight of the structure and loads applied are transferred to the piers.

![Pier & Capping Beam Diagram](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_foundation_types_pier_diagram_5785f1ccce.gif)
_Figure 7: Pier & Capping Beam Diagram ([Reference](https://www.dlsweb.rmit.edu.au/Toolbox/buildright/content/bcgbc4010a/09_footing_systems/07_pier_beam/page_004.htm))_

Pier foundations are often used in areas where the soil is too weak to support the weight of a traditional foundation, or where the ground is prone to shifting or settling. Piers are deeper than other residential foundations and can be used to reach deeper stronger soils that have higher bearing pressures and can carry more load. The piers are typically placed at regular intervals around the perimeter of the building, or in a grid pattern across the entire area of the foundation. The piers can be designed to be either precast and driven into the ground or bored and constructed in situ, depending on the soil conditions and the load requirements of the structure.

One advantage of pier foundations is that they can be designed to accommodate variations in soil conditions or building loads, making them a versatile foundation option. 

When piers are precast and driven, construction time can be greatly reduced, making them a popular choice for smaller buildings and residential homes. Pier foundations typically require large machinery to bore a deep hole or drive a precast unit into the soil which usually need a large working area and temporary works design done for bearing pads for the heavy equipment.

![Example of Pier Foundations in a Residential Building](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_foundation_types_pier_example_1cfb31ef66.jpg)
_Figure 8: Example of pier foundations in a residential building ([Reference](https://plasticinehouse.com/pier-and-beam-foundation/))_

### Basement Foundations

A basement foundation is a type of foundation that provides living or storage space below the main level of a building. It is suitable for buildings on sloping sites or in areas with limited land space. A basement foundation can be constructed using either a concrete or masonry retaining wall system.

The design of a basement foundation involves calculating the load of the building and the soil-bearing capacity to determine the depth and size of the foundation walls. The design of a basement foundation is more detailed than other residential foundation designs, as active and passive pressure analysis of the soil must be performed to design the walls and ensure they have sufficient capacity to retain the lateral load of the adjacent soil. 

![ Basement Foundation Diagram](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_foundation_types_basement_footing_87bd3e56c8.png)
_Figure 9:  Basement foundation diagram ([Reference](https://foundationhandbook.ornl.gov/handbook/section2-1-structure.shtml))_

Basement foundations require significant excavation to create room for the basement itself. The walls are then constructed using either poured concrete or masonry units, which are reinforced with steel bars or mesh to increase their strength and durability.

The benefits of basement foundations include their ability to provide additional living or storage space, which provides the potential to increase property value, and their resistance to weather and natural disasters. However, limitations include the potential for water infiltration and moisture issues, the need for proper ventilation and insulation, and the higher construction costs associated with excavating and building below ground level. 

They can also be susceptible to water infiltration, mold, and difficulty accessing plumbing and electrical systems due to the depth that building services are typically installed. Basement foundations also require the installation of drainage systems and waterproofing to prevent water damage.

![Basement Foundation Construction](https://clearcalcs-prod2-cms.s3.amazonaws.com/BLOG_foundation_types_basement_example_9ee59cb6c6.jpg)
_Figure 10: Basement foundation construction ([Reference](https://mtcopeland.com/blog/3-types-of-basement-foundations-to-know/))_

### Crawl Space Foundations

A crawl space foundation is a type of foundation that provides a shallow space between the ground and the main level of a building. It is suitable for buildings on level ground or with minimal slope. A crawl space foundation can be constructed using either a concrete or masonry wall system.

The design of a crawl space foundation involves calculating the load of the building and the soil-bearing capacity to determine the depth and size of the foundation walls. 

![Crawl Space Foundation Diagram](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_foundation_types_crawl_space_diagram_3c5a021e01.jpg)
_Figure 11: Crawl space foundation diagram ([Reference](https://www.pinterest.com.au/pin/9640586674698628/))_

Like basement foundations, the design of a crawl space foundation requires active and passive pressure analysis of the soil that must be performed to design the walls and ensure they have sufficient capacity to retain the lateral load of the adjacent soil. 

However, the depth of excavation for a crawl space foundation is much shallower than a basement foundation which means that the walls are not required to have a significant load capacity such as basement foundations. The internal load-bearing members in a crawl space foundation can be piers or strip footings. 

The benefits of crawl space foundations include their ability to provide access to plumbing and electrical systems, their potential to improve indoor air quality by providing ventilation, and their lower construction costs compared to basement foundations. However, limitations include the potential for moisture and pest issues in the crawl space, the need for proper ventilation and insulation, and the potential for settling and cracking if the soil is not properly compacted.

Unlike other types of foundations, crawl space foundations require the installation of a ventilation system to prevent the buildup of moisture and humidity. Another difference is that crawl space foundations can be more expensive than concrete slab foundations due to the additional excavation and installation of a ventilation system.

![Crawl Space Foundation with Piers](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_foundation_types_crawl_space_example_685e838fea.jpg)
_Figure 12: Crawl space foundation with piers ([Reference](https://www.researchgate.net/figure/Example-of-an-Open-Crawl-Space-with-a-Pier-Foundation_fig2_273458708))_

## Conclusion

While providing an accurate cost estimate for each type of foundation is difficult without specific project information, there are some general cost ranges that can be used as a guide. 

![A summary of different foundation types and their cost, benefit and structural issues.](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_foundation_types_summary_7406d4d28c.png)

It is important to note that these costs can vary greatly depending on factors such as the location of the project, the availability and cost of materials, and the complexity of the design.

Design and construction methodologies can also vary between the different types of foundations. 

For example, spread footings typically require excavation and the pouring of separate concrete footings, while raft foundations require the pouring of a single, continuous concrete slab. Basement foundations require excavation and the construction of walls and a floor, while crawl space foundations require the construction of walls and a raised floor. 

The design and construction procedures for each type of foundation should be considered along with the budget and the specific needs of the building and the site.

Foundation crack, sinking, or leak repairs can range from $200 to $7000 and sometimes require significant temporary works designs to prop the building. 

Most of the structural issues for each foundation can be overcome by proper soil analysis by a qualified engineer, as well as careful construction quality procedures in accordance with local building standards to ensure the longevity of the foundations.

ClearCalcs has a streamlined design process for [Concrete Spread/Pad Footings](https://clearcalcs.com/calculations/us/foundationsSpreadFootingUSAACI318-19), wall footings [Concrete Strip/Wall Footings](https://clearcalcs.com/calculations/us/foundationsWallFootingUSAACI318-19) (continuous spread footing), [Concrete Pier Footings (IBC 2021)](https://clearcalcs.com/calculations/us/foundationsPierFootingUSAACI318-19), and [Cantilever Retaining Walls](https://clearcalcs.com/calculations/us/retainingWallCantileverUSAACI318-19) that can greatly assist in the design of basement foundations and crawl space foundations according to the ASCE 7 standards with references to the American Concrete Institute for the US as well as [AS 3600](https://clearcalcs.com/standards/SA/AS-3600-2018-0) for Australia.

This article will discuss the different types of foundations used in residential buildings, their applications, pros, and cons.

Different Types of Foundations in Residential Design, Their Applications, Pros, and Cons

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Supports and connections are key components of the structural design process. 

Understanding the various types of supports and connections in structural design is critical for structural engineers, architects, and building designers. This is especially important to build safe buildings, particularly when it comes to determining the load and tributary width in residential buildings.

This article will examine different types of support utilized in structural design, as well as their advantages and disadvantages. We will go through fixed support, pinned support, and roller support, as well as their basic attributes, frequent usage and application in homes or light commercial structures, and actual instances.

## Definition of Support in Structural Engineering

In structural engineering, a support is a structural part or system that transfers loads to the foundation while limiting a structure's motion in certain directions and allowing it to move in others. Supports are sometimes defined as "constraints given at the ends of structural components to prohibit translation, rotation, or both". 

[Beams](https://clearcalcs.com/calculations/us/timberBeamASD), [columns](https://clearcalcs.com/calculations/us/timberColumnASD), [walls](https://clearcalcs.com/calculations/us/timberShearWallASD), and [foundations](https://clearcalcs.com/calculations/us/foundationsSpreadFootingUSAACI318-19) are examples of supports in real-world constructions.

### Roles of Support in Structural Design and Why It's Important

Supports are critical to the stability and safety of structures in structural engineering. Support systems distribute loads and pressures from the structure to the base, preventing collapse brought on by too much stress. 

Therefore, structural engineers, architects, and building designers must have a solid understanding of the functions of support in order to create buildings that are both effective and safe.

#### Distributing Loads

In structural design, distributing loads and forces is one of the main functions of supports. 

Gravitational, wind, and seismic loads are only a few types of loads that buildings are susceptible to. Therefore, determining the size and direction of these loads when constructing a structure is crucial to make sure the support system can manage them by transferring the loads from the foundation to the ground.

#### Controlling Deflection

Controlling deflection is another crucial function of supports in structural design. 

When a structure deflects, it moves or deforms to some extent in response to a load. A structure's integrity and safety might be compromised by excessive deflection. Deflection is restricted to allowable limits by supports like beams, columns, and walls. 

Deflection can be significantly reduced by adjusting a support's [tributary width](https://clearcalcs.com/blog/what-is-load-and-tributary-width-in-structural-design-an-overview). The part of the floor or roof that the support system directly supports is referred to as the tributary width. A wider tributary allows a support system to carry a heavier load, which reduces deflection.

#### Providing Stability

Moreover, supports provide building stability. A stable structure is one that can withstand loads and external influences without collapsing. 

By resisting lateral loads like [wind](https://clearcalcs.com/calculations/us/loadsWindCnCASCE7-16) or [earthquake loads](https://clearcalcs.com/calculations/us/seismicAnalysisUS), supports like walls, braces, and [shear walls](https://clearcalcs.com/calculations/us/timberShearWallASD) give stability. The stability of the structure depends heavily on the placement and design of these supports.

#### Reducing Vibrations

Furthermore, supports aid in reducing vibrations inside a building. Many factors, like wind, traffic, or seismic activity, can cause vibrations. 

In addition to making inhabitants uncomfortable, excessive vibrations may threaten the building's structural integrity. 

To lessen vibrations in a structure, supports such as foundation isolators, tuned mass dampers, and dampers are used. Although tuned mass dampers dampen vibrations by oscillating in the opposite direction from dampers, dampers absorb energy from the vibrations. 

In order to reduce vibration transfer to the structure, base isolators are utilized to isolate the building from the ground.

## Different Types of Support

![Different types of supports, the movement they restrict, and reaction forces ](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_support_types_comparison_c16af0cfd7.png)
_Figure 1: Different types of supports, the movement they restrict, and reaction forces ([Reference](https://support.clearcalcs.com/article/148-how-to-enter-beam-supports-imperial-units))_

### Fixed Support

![A diagram illustrating fixed support](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_support_types_fixed_diagram_ef00affc67.png)
Fixed supports can withstand a turning moment as well as horizontal and vertical forces. 

They are also known as stiff supports since they prevent both rotation and translation (in the context of support structures, translation refers to the movement of a structure or component in a straight line without rotation or angular displacement). This means that for a structure to be stable, there only has to be one fixed support.

#### Common Use and Application in Residential or Light Commercial

In [residential](https://clearcalcs.com/use-case/residential-design) or light commercial construction, fixed supports are frequently employed, especially for single-support applications. 

These are often required for cantilevered constructions like balconies and overhangs, where the fixed support provides all the essential limitations to ensure the structure is secure. 

Fixed support can also transfer moments between structural components, which is an important aspect of structural design.

#### Benefits and Limitations of Fixed Support

There are many advantages to using fixed supports for a building, but perhaps the most important is that they guarantee the most rigidity and stability for the building. 

As a result, they are highly recommended for use in areas prone to earthquakes and other situations calling for a rock-solid foundation. If a building has only one support column, they come in handy there, too.

Nonetheless, the fixed supports' rigidity can sometimes be a drawback. They are rigid and cannot bend or sway, which can cause difficulties. Sometimes, the safety of adjacent materials necessitates that a structure has some wiggle room, or deflection. 

The durability of the support may also be compromised due to the expansion of materials like concrete if the support is improperly designed.

![An image showing an example of fixed support on a structure](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_support_types_fixed_example_0e1bbac22b.jpg)
_Figure 2: An example of a fixed support ([Reference](https://www.shutterstock.com/image-photo/large-screw-hexagon-flange-nut-supporting-2024814764))_

### Pinned Support (Hinge Support)

![A diagram illustrating pinned or hinge support](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_support_types_pinned_hinge_diagram_67d39d0372.png)
A pinned support can withstand both vertical and horizontal stresses, but not momentary ones. 

They will permit rotation but not translation of the structural member in either direction. Even if they might only resist a small amount of moment, many connections are presumed to be pinned connections.

It is also true that a pinned connection might only permit rotation in one direction while obstructing rotation in all other directions. Usually, a structure cannot be made stable with just one pinned connection. To keep the structure from rotating, another support must be added at some point. Both horizontal and vertical forces are depicted in the illustration of a pinned support.

#### Common Use and Application in Residential or Light Commercial

Pinned supports are commonly used in residential or light commercial applications for joining multiple members together, such as in [trusses](https://clearcalcs.com/blog/what-is-truss), three-hinged arched bridges, and simply supported beams. 

They are also used in other structures where rotation is needed, such as in cranes, towers, and other similar structures.

#### Benefits and Limitations of Pinned Support

One major benefit of pinned supports is that they may be rotated, making it much simpler to join together many members. Not only are they simple to design for, but they also eliminate the need for moment-resisting components.

Yet the main drawback of pinned supports is that they can't hold the whole structure down by themselves. For anchorage, at least two pins are required, and the pins themselves are helpless against any moments that might be applied to the structure. 

Since extra supports or moment-resisting components may be required to ensure the stability and safety of structures with pinned supports, this restriction might complicate their design.

![An image showing an example of pinned support](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_support_types_pinned_example_14bb6743c5.png)
_Figure 3: An example of a pinned support ([Reference](https://www.quora.com/What-is-the-meaning-of-pin-support-and-roller-support-in-real-life-example))_

### Roller Support

![A diagram showing roller support](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_support_types_roller_diagram_cb2c8a20e7.png)
Roller supports are free to move laterally but can only withstand perpendicular stresses. They enable motion along surfaces devoid of opposition from horizontal forces. The surface may be vertical, horizontal, or inclined in any direction. 

These supports allow for horizontal movement while enduring significant vertical stresses. Horizontal movement is crucial, especially when the structural member is expanding and contracting. They guard against a pinned support being damaged. 

Rubber bearings or gears are two examples of roller supports. Think about a load on roller skates, for instance. If there is no horizontal force, the weight is held in place. Yet, the body begins to move as soon as a horizontal force is applied.

#### Common Use and Application in the Residential or Light Commercial

Long-span constructions, such as bridges, often use roller supports because of the large shifts that thermal expansion can induce.

Roller supports are commonly employed in residential and light commercial construction for applications where thermal expansion is a factor, such as with metal roofing systems or long-span wood trusses, pipes and other constructions like them that need a lot of wiggle room in their support systems.

#### Benefits and Limitations Of Roller Support

The fundamental benefit of using roller supports is that they allow for unrestricted rotation and movement in a single direction. This safeguards a structure from potential damage due to temperature changes or other external influences.

However, due to their inability to sustain lateral loads, roller supports are not suitable for structures that must endure them. As they may move wherever they like, they are not as stable as a fixed one would be.

![An image showing an example of a roller support](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_support_types_support_example_d6dd63a80a.jpg)
_Figure 4: An example of a roller support ([Reference](https://theconstructor.org/structural-engg/types-of-supports-reactions-uses-structures/16974/))_

### Frequently Asked Questions (FAQs) When Designing with Supports for Residential Projects

#### Which is the weakest kind of support?

The weakest kind of support is simple support (roller support), as it provides no restraint for a structure.

#### How should supports in a residential design project be sized and placed?

The load capacity and stresses that the structure would be subjected to are normally calculated by a structural engineer or architect while designing supports. The required supports' size and placement will be determined in part by this.

#### Why are supports important in residential design projects?

Supports give the structure strength and stability, especially in places where there are significant loads or where more support is required.

#### Which materials are frequently employed as supports in residential design projects?

Concrete, steel, and wood are frequently utilized as supports. The material selection will be determined by the building's design, the required load capacity, and additional elements like price and availability.

## Conclusion

The role of supports and connections in structural design is critical to ensuring the safety and stability of buildings. These components distribute loads and pressures, limit deflection, offer stability, and decrease vibrations. 

There are various types of supports, such as fixed, pinned, and roller supports, each with advantages and disadvantages. Knowing the many types of supports and connections is critical for structural engineers, architects, and building designers to produce effective and safe buildings.

#### References
- Connor, J. J., & Faraji, S. (2013). Fundamentals of Structural Engineering (2nd printing, corrected). Springer Science Business Media, LLC.
- Chen, Wai-Fah, and Eric M. Lui, eds. Handbook of Structural Engineering. CRC Press, 2005.
- American Society of Civil Engineers. (2010). Minimum design loads for buildings and other structures. SEI/ASCE 7-10. Reston, VA: American Society of Civil Engineers.

This article will explore why support is important in structural design and examine different types of support commonly used in structural design, as well as their advantages and disadvantages.

Support and Connection Types in Structural Design

An image showing portal frames in an empty warehouse by Weerasaksaeku from Canva

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## What is Load Path in Structural Design?

Load path refers to the route by which the weight of a structure and live loads are transmitted from their point of application to foundation and finally to the ground.

A load path is typically composed of a series of structural members, including [beams](https://clearcalcs.com/calculations/us/timberBeamASD), [columns](https://clearcalcs.com/calculations/us/timberColumnASD), [wall](https://clearcalcs.com/calculations/us/timberShearWallASD)s, and [foundations](https://clearcalcs.com/calculations/us/foundationsSpreadFootingUSAACI318-19). An efficient load path design helps to distribute the loads throughout the structure, preventing any one component from being overloaded.

###  Why is Load Path Important in Structural Design?

The proper design of a load path is critical to the structural integrity of a building. A deliberately designed [load path ensures that the weight of the structure is transferred from the roof to the foundation](https://support.clearcalcs.com/article/24-linking-reactions-between-beams-and-columns-load-path-tracking) in a safe and efficient manner. 

A poorly designed load path can result in a building that is not structurally sound, leading to potential safety hazards and costly repairs. Therefore, understanding the load path and its mechanism is crucial for structural engineers, architects, and building designers.

## Types of Load Path

There are two main types of load paths in building design: Gravity Load and Lateral Load.

### Gravity Load Transfer Example

Gravity load transfer refers to the process by which the weight of a building is transferred down through the structural components to the ground. 

In a residential structure, the weight of the building is supported by the foundation, which is typically made of reinforced concrete.

Consider a two-story house. First, the roof, walls, and floors are transferred to the foundation through load-bearing walls, columns, and beams. These structural components distribute the weight evenly, so no single point of the foundation is overloaded. The foundation transfers the load to the ground, providing the necessary support to prevent the building from collapsing.

Gravity loads can consist of both dead and live loads. Dead loads are permanent loads that are always present in the building, such as the weight of the structure, roofing materials, and fixed equipment. Live loads, on the other hand, are temporary loads that may change over time, such as people, furniture, and snow loads.

In a typical residential structure, the dead load is transferred from the roof to the foundation through the load path discussed earlier. The live load, however, often requires a different load path mechanism as this load can be cyclical in nature and is applied laterally rather than vertically in the case of wind and earthquake load. The live load is usually distributed across the floor joists, which transfer the load to the supporting walls and then down to the foundation. The load path for the live load is designed to prevent any one component from being overloaded, ensuring the structural integrity of the building.

![A diagram illustrating gravity load transfer in residential building](https://clearcalcs-prod2-cms.s3.amazonaws.com/BLOG_load_transfer_gravity_load_residential_7615d7b277.png)
_Figure 1: Gravity load transfer in a residential building ([Reference](https://www.reddit.com/r/EngineeringStudents/comments/ijwo7a/does_my_loading_path_diagram_make_sense/))_

![A diagram illustrating gravity load transfer in a commercial building](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_transfer_gravity_load_commercial_a1518def90.jpg)
_Figure 2: An example of gravity load transfer in a commercial building ([Reference](https://sites.google.com/site/ae390papadakis/load-path-diagrams))_

### Lateral Load Transfer Example

Lateral loads, such as wind and seismic loads, are live loads (temporary imposed loads) that act horizontally on a building. 

Lateral loads require a different type of load path than gravity loads. In order to resist lateral loads, buildings typically use shear walls, moment frames, steel bracing, or a combination of them. 

Shear walls are designed to resist lateral forces by transferring them to the foundation through the building's floors, walls, and roof. 

Moment frames, on the other hand, resist lateral forces by creating a rigid frame that can resist bending forces by fixed connections that transfer load to the footings. Both of these load path mechanisms help to ensure that the building can withstand lateral loads without suffering any structural damage.

![A diagram showing an example of lateral load path in residential buildings](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_transfer_lateral_residential_3bdef97273.png)
_Figure 3: An example of lateral load path in residential buildings ([Reference](https://codes.iccsafe.org/content/CHIBC2019P5/about-the-chicago-construction-codes))_

![A diagram illustrating lateral load transfer in a commercial building](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_transfer_lateral_commercial_c11e5b9cc8.jpg)
_Figure 4: An example of lateral load path in a commercial building ([Reference](https://sites.google.com/site/ae390papadakis/load-path-diagrams))_

## Examples of Load Paths in Common Structures

There are many different types of load paths that can be used in building design. Here are three examples of load paths used in common structures:

### Timber Residential Structure Load Path

A residential timber structure typically uses a gravity load path to transfer the weight of the roof to the foundation as residential structures are less susceptible to wind and load path than mid-high rise buildings meaning the dead loads are the critical design actions.

![A diagram illustrating load path for a timber residential structure](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_transfer_residential_timber_2_85d982afbe.jpg)
_Figure 5: Load path for a timber residential structure ([Reference](https://www.nachi.org/structural-design-wood-framing-home-inspector.htm))_

The roof load is transferred to the ridge beam, which is then supported by the roof rafters. The rafters are connected to the wall plates, which are in turn supported by the studs. The studs transfer the weight to the sole plate, which rests on the foundation. In this load path, each structural member supports the weight of the components above it, transferring the load to the foundation.

### Concrete Commercial Building Load Path

In a concrete commercial building, the load path is usually designed to handle a critical load combination that is specified in design standards that combines gravity loads and lateral loads (earthquake load and wind load) as the actions of wind and earthquake loads are more severe on taller buildings. 

![A diagram showing load path for a high rise building](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_transfer_load_path_commercial_c37f27eac5.png)'
_Figure 6: Load path for a high rise building ([Reference](https://sites.google.com/site/a7nesbittbuildinganalysis/structural-system))_

Gravity (vertical) loads are transferred from the roof to the foundation via the slabs to the columns and down into the piles. 

However, lateral (horizontal) loads, such as [wind](https://clearcalcs.com/calculations/us/loadsWindCnCASCE7-16) or [seismic](https://clearcalcs.com/calculations/us/seismicAnalysisUS) forces, require a different load path mechanism. Lateral loads are transferred to the walls and then down to the foundation through [shear walls](https://clearcalcs.com/calculations/us/timberShearWallASD) or moment frames. The foundation then resists the lateral loads by transferring them to the surrounding soil.

### Steel Portal Frame Load Path

A steel [portal frame](https://clearcalcs.com/calculations/us/portalFrameAnalysis) is a commonly used load-bearing system in industrial and commercial buildings. 

![An image of steel portal frame in construction](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_transfer_load_path_portal_frame_0ab53b3cd1.jpg)
_Figure 7: Portal frames have simple load paths ([Reference](https://structville.com/2019/06/preliminary-plastic-analysis-of-portal-frames.html))_

This type of structure uses a portal frame to transfer loads from the roof to the foundation. The roof load is transferred to the rafters (secondary beams), which are supported by the purlins (primary beams). The purlins are then bolted to the columns via a welded end plate, which transfers the load to the foundations. The columns can be rigid or braced in a steel portal frame to resist both gravity loads and lateral loads.

## Conclusion

In conclusion, the load path is a critical component of building design. It ensures that the weight of the structure is transferred from the roof to the foundation in a safe and efficient manner, preventing any one component from being overloaded. 

By designing the proper load path mechanisms, buildings can be designed to resist gravity loads, lateral loads, and other environmental factors, ensuring the safety and longevity of the structure. 

With this understanding, the design of residential and commercial structures can be optimized for safety, efficiency, and longevity. Clear Calcs can be used for [Load Path Tracking](https://www2.clearcalcs.com/videos/load-path-tracking), where a user can link reactions between beams, columns, and foundations to track loads through a structure dynamically, and can even be used to [Link Loads and Reactions Between Calculators](https://support.clearcalcs.com/article/24-linking-reactions-between-beams-and-columns-load-path-tracking). 

These features can dramatically streamline the design process as the loads applied to subsequent members in the load path will be updated automatically when a parameter is changed in a member that is bearing upon that load path. This can produce a much more structurally efficient building, reducing cost and time during design and construction.

This article aims to give a general overview of the concept of a load path and why it is important in structural design.

Load Transfer in Residential Structures: From Roof to Foundation

Steel trusses from an airport hanger by jeffhochstrasser from Canva

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Roof steel trusses are common structural systems used to design and construct various buildings, including residential, commercial, and industrial structures, to span large distances (Heyman, 2010). These trusses consist of a series of interconnected steel members, typically arranged in a triangular pattern, that provide support and stability for the roof. 

The design and analysis of roof steel trusses are critical to ensuring the structural integrity and safety of the building. 

This article discusses the approach to analyzing and designing a steel roof truss by providing a typical case study and comparing various tools commonly used to analyze truss design. We will cover: 
- Important factors to consider when designing and analyzing trusses
- Modeling assumptions in truss analysis 
- A practical example of how to analyze and design a Pratt roof truss for a building to American standards

## Introduction

In the United States, the design and analysis of roof steel trusses are typically based on the [American Institute of Steel Construction (AISC)](https://www.aisc.org/) [360-22: Specification for Structural Steel Buildings (AISC, 2022)](https://www.aisc.org/products/publication/standards/aisc-360/specification-for-structural-steel-buildings-ansiaisc-360-16-download2/). 

This specification provides guidelines for the design, fabrication, and erection of structural steel for buildings and other structures such as bridges and towers. The AISC specification includes specific provisions for the design and analysis of roof steel trusses to ensure that they can withstand the various loads and stresses they may be applied to during their lifetime. 

The first step in designing a steel roof truss is to determine the loads to which the truss will be subjected. These loads include dead loads, which are the weight of the roof itself and any permanent equipment or structures attached to it, as well as live loads, which are the weight of temporary items that may be present on the roof. 

In addition, the truss may be subjected to [wind loads](https://clearcalcs.com/calculations/us/loadsWindCnCASCE7-16), which are caused by the wind blowing on the roof, and snow loads, which are caused by the weight of snow that may accumulate on the roof. 

Once the loads have been determined, the design engineer can begin to determine the appropriate size and configuration of the steel members that will make up the truss. This typically involves using computer software that can perform complex calculations to determine the optimal design. Some of the factors considered are the strength of the steel members, the distance between the members, and the angle of the members relative to one another. 

## Design Factors in Steel Trusses

When designing a steel roof truss using American standards, structural designers must consider several essential factors to ensure that the roof is safe, durable, and capable of withstanding the loads and stresses that it will be subjected to over time. 

### Applied Loads

Applied loads are divided into gravity and lateral loads. 
- **Gravity loads** typically subjected to a truss include dead loads (the weight of the roof itself), live loads (the weight of any objects or people on the roof), and snow loads. 
- **Lateral forces** typically imposed on a truss structure include wind and [seismic loads](https://clearcalcs.com/calculations/us/seismicAnalysisUS), which must also be considered when designing a steel roof truss using the American standard. 

In this regard, American standards requirements must be carefully evaluated to ensure that the roof is designed to support the necessary loads without collapsing or experiencing excessive deflection.

### Material Selection

Another key consideration when designing a steel roof truss is the material selection, as it will determine the overall strength and durability of the roof. 

The American standard [AISC 360-22: Specification for Structural Steel Buildings](https://www.aisc.org/products/publication/standards/aisc-360/specification-for-structural-steel-buildings-ansiaisc-360-16-download2/) provides guidelines for the steel's minimum yield strength and other properties, as well as the allowable stress levels. 

Examples of steel materials include:
- [A36](https://en.wikipedia.org/wiki/A572_steel): This is the most commonly used structural steel grade, with a minimum yield strength of 250 MPa (36 300 psi). It is suitable for most truss applications, particularly where the load is not too high. 
- [A572](https://en.wikipedia.org/wiki/A572_steel): This grade is used for heavy loads requiring higher strength and is available in several grades, including 42, 50, 55, 60, and 65. 
- [A992](https://en.wikipedia.org/wiki/ASTM_A992): This is the newest grade of structural steel and has a minimum yield strength of 345 MPa (50 000 psi). It has a higher strength-to-weight ratio than A36 and A572, making it suitable for long-span trusses with heavy loads.
- [A500](https://en.wikipedia.org/wiki/ASTM_A500): This grade is carbon steel generally used in steel tubing, where truss elements are typically made. Like A572, it has multiple grades and classes depending on the section constructed. This grade is the most used in the HSS sections that are widely adopted in roof trusses.

### Section Selection

Various structural sections can be used when erecting a steel roof truss, depending on the design and loading requirements. Some common structural sections used in steel roof truss construction include:
- [**Hollow structural sections (HSS)**](https://steeltubeinstitute.org/hollow-structural-sections/product-overview-benefits/#:~:text=The%20term%20Hollow%20Structural%20Sections,a%20variety%20of%20manufactured%20products.): These are steel tubes that can be square, rectangular, or circular in shape and are commonly used as truss members.
- **Angles**: These are L-shaped sections that are commonly used to connect the various members of a truss, such as the chords and web members.
- **Channels**: These are U-shaped sections that can be used as chords or web members in a truss.
- **Pipes**: Steel pipes can also be used as truss members and are often used as tension members in trusses.
- **I-beams**: Also known as W-beams or wide flange beams, these sections have an I-shaped cross-section and can be used as truss chords.
- **Tee sections**: These sections have a T-shaped cross-section and can be used as chords or web members in a truss.

The selection of the appropriate structural sections for a steel roof truss depends on factors such as the span, the loading requirements, the design criteria, and the available materials.

### Truss Geometry

Truss geometry is another critical factor when designing a steel roof truss. 

In general, truss geometry refers to the physical dimensions and layout of a truss structure. The height and width of a truss are typically determined by the specifications of the structure it is intended to support. 

For example, the height of a roof truss might be based on the desired slope or pitch of the roof, while the width might be determined using the overall width of the building or the spacing between support columns. The number of unit panels that make up the truss width can vary depending on the design and the load-bearing requirements of the structure. Typically, a truss is composed of a series of interconnected triangles that distribute weight and stress evenly throughout the structure. 

The number of triangles, and therefore the number of unit panels, depends on the size and shape of the truss. Generally, these parameters are selected based on the architectural contexts, the owner's preferences, and some structural and construction limitations, which vary from one case to another. 

Currently, various types of trusses can be used in a steel structure. 

In general, the truss geometry selected must be followed closely to ensure that the truss is designed to provide adequate strength and stability while minimizing the amount of material required and meeting the architects' and owners' objectives. Examples of common truss geometries and descriptions of various types of trusses can be found in [this article](https://clearcalcs.com/blog/types-of-roof-trusses). 

### Fire Resistance

Fire resistance is also important when designing a steel roof truss, where the roof is expected to meet certain fire resistance ratings as specified in American standards, such as the [AISC 360](https://www.aisc.org/products/publication/standards/aisc-360/specification-for-structural-steel-buildings-ansiaisc-360-16-download2/) and the [National Fire Protection Association (NFPA)](https://www.nfpa.org/)'s standards [NFPA 5000](https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=5000) and [NFPA 220](https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=220).

## Modeling Assumptions

Truss elements are typically considered pin-connected because they are designed to primarily resist axial loads (tension or compression) and not bending moments.

A pin connection between the truss members is a simple hinge or pin joint, which allows the members to rotate freely relative to one another. 

This type of joint is also known as a pinned or hinged joint, and it is a common feature in truss structures. The reason for using pin-connected joints in truss structures is that no shear or bending forces are transferred from one member to another, and only axial forces are transferred in between members. 

In contrast, frame elements such as beams are designed to resist both axial, shear, and moment loads, and they are usually connected using fixed or semi-fixed (moment-resistant) connections. These connections can resist axial and shear loads and bending moments but are typically more complicated to analyze than pin-connected joints. 

Nevertheless, in some design cases, truss elements are considered frame elements, given that they are welded elements that pose certain resistance against rotation. 

Another design assumption is typically made in which the chords are frame elements while the diagonal and vertical elements are truss elements (pinned at the ends). 

This assumption emerges from the fact that the chords are typically made of a single continuous steel element that poses rigidity, whereas the diagonal and vertical elements are welded to the chords. Hence, the connections between diagonal and vertical elements and the chords are approximated as pinned to simplify calculations while efficiently resisting axial loads, even though they are physically welded. This approach acknowledges that the actual behavior of the structure might deviate slightly from the assumptions made.

In this section, a comparison between various joint connection assumptions will be provided for a typical truss case. 

Let us consider a typical [Warren truss](https://clearcalcs.com/blog/types-of-roof-trusses), as shown in Figure 1. Assume that the loads applied include the self-weight of the truss as well as a 685 lb/ft uniformly distributed force on the top chord.

![n example of a Warren truss subject to a 685 lb/ft distributed load](https://clearcalcs-prod2-cms.s3.amazonaws.com/BLOG_truss_example_Warren_truss_f7289fd592.png)
_Figure 1: An example of a Warren truss subject to a 685 lb/ft distributed load_

Figure 2 shows the results of the analysis for three various cases. 

![Truss analysis based on various joint analysis using ETABS and ClearCalcs](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_example_various_joint_analysis_62a62a429d.png)
_Figure 2: Truss analysis based on various joint analysis_

Additionally, Table 1 summarizes the peak internal forces and bending moments. 
![Comparison between the maximum forces/moments under various joints' assumptions](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_example_joint_analysis_table_d894ca732d.png)
_Table 1: Comparison between the maximum forces/moments under various joints' assumptions_

It can be seen that all forces are close in value, with the highest internal axial force being observed in all pinned cases and the highest tension bending moment in pinned/continuous, whereas the highest compression bending moment is achieved in the continuous case.

## Design Example

The design example herein is a [Pratt roof truss](https://clearcalcs.com/blog/types-of-roof-trusses) design assumed to be located in Texas, USA. The building has a length of 131 ft and a width of 29.4 ft. 

### Defining the Truss Geometry

In this example, the roof truss is taken with a height of 4.9 ft and six unit panels, each with 4.9 ft in width. 

![An image showing a Pratt roof truss with a length of 131 ft and width of 29 ft](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_example_Pratt_roff_truss_f9f31f39ff.png)
_Figure 3: Description of the Pratt roof truss design example adopted in this article_

### Selecting Truss Material and Section 

The truss is assumed to be built of A500 steel grade. The selection of the material is typically based on the availability in the market and the intended level of stress to be applied. For instance, the A500 grade offers a 6,620,682 lb/ft2 yielding strength, which is a good value for a roof truss application. 

Once the material is selected, the next step is to select the steel section. Various sections can be found in the AISC specifications. However, a truss is commonly made of hollow square or rectangular sections. For this reason, the square hollow structural section HSS3-1/2X2-1/2X.250 section is selected as the initial guess during the design for all elements, and its capacity will be checked once the load analysis is completed. Thereafter, the section size can be optimized based on the demand/capacity ratio for the tension and compression section in the top and bottom chords, as well as the diagonal and vertical elements. 

Accordingly, the process of selecting the truss material and section is the truss design stage in which the properties of the truss are all set.

### Calculating Total Distributed Loads

The gravity loads (dead and live loads) are typically applied to the top and bottom chords of a truss in different ways, depending on the specific design and intended usage of the truss. 

For example, in a pitched roof truss, the gravity loads are applied to the top chord of the truss. The bottom chord may also be designed to resist the weight of any occupants or equipment that may be located in the attic space. 

A similar concept is also used in floor trusses, where the gravity loads are typically applied to the top chord of the truss, while the bottom chord carries the weight of occupants, furniture, and other moveable objects. 

In this example, the truss is designed to support gravity loads, including both dead (342 lb/ft) and live (154 lb/ft) loads. These loads are obtained by distributing the roof loads to the truss and then are applied as line loads during the analysis, and the combination given in Eq. 1 is used as recommended by the American standard. 

Load combination = 1.2 Dead load + 1.6 Live load (Eq. 1)

Figure 4 shows the results for the truss analyses using the ETABS and the [ClearCalcs Truss Analysis Wizard](https://clearcalcs.com/calculations/us/trussAnalysis). It is evident that the results from ClearCalcs match with the results from ETABS, as seen in Figure 5. 

Additionally, it can be seen that the maximum axial load is about 14,400 kN and 12,700 kN for compression and tension. These values must be taken to check whether the selected section provides sufficient capacity to resist the applied loads. 

Accordingly, based on the selected material and section properties, the HSS3-1/2X2-1/2X.250 section provides sufficient capacity, as highlighted in the AISC specifications.

![An diagram showing analysis results for a Pratt roof truss obtained with ClearCalcs and ETABS](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_example_results_Clear_Calcs_ETABS_72814dc13f.png)
_Figure 4: Results of the Pratt roof truss analysis using ETABS and ClearCalcs_

## Conclusion

Based on the aforementioned statements, the following conclusions can be drawn: 
- The American Institute of Steel Construction (AISC) specification provides guidelines for the design, fabrication, and erection of structural steel for buildings and other structures.
- To ensure structural integrity and safety, the loads to which the truss will be subjected must be carefully determined. 
- The material selection is critical to ensuring the overall strength and durability of the roof, and the American standard provides guidelines for the steel's minimum yield strength and other properties, as well as allowable stress levels. 
- Truss geometry is an important factor to consider when designing a steel truss roof, where various types of trusses can be used in a steel structure. 
- Truss elements are typically pin-connected, allowing for efficient resistance to axial loads without inducing significant bending stresses or moments, but in some cases, they may be considered continuous, posing resistance against rotation and inducing lower axial force compared to pin connections. 
- Trusses' force analyses can be time-consuming when performed manually; however, using a professional tool can save huge efforts while yielding accurate and reliable results.

Overall, the practical analysis and design of steel roof trusses require careful consideration to ensure a safe and durable structure capable of withstanding the loads and stresses it may encounter over time. [ClearCalcs Truss Analysis Wizard](https://clearcalcs.com/calculations/us/trussAnalysis) can easily determine the cumulative load applied, support reactions, bending moment, shear and axial forces, extension and displacement for each chord of the truss by inputting the truss geometry and load conditions.

#### Ready to start calculating in ClearCalcs?

[You can use the account for 14 days for free](https://clearcalcs.com/signup), with no commitment required. Need ClearCalcs for a one-off project? Subscribe to our month-to-month plan and cancel anytime, no questions asked.

#### References 
- AISC. (2022). AISC 360-22: Specification for Structural Steel Buildings. 
- Heyman, J. (2010). Design of a simple steel truss. 


This article discusses the approach to analyzing and designing a steel roof truss by providing a typical case study and comparing various tools commonly used to analyze truss design.

Practical Analysis and Design of Steel Roof Truss According to American Standards

An image showing the interior frame of an American residential house under construction by valentynsemenov from Canva

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One of the key concepts in structural design is [load tributary width](https://support.clearcalcs.com/article/170-what-is-tributary-width), which refers to the area of a structure that is supported by a particular load. 

In this article, we will explore what load tributary width is, why it is important in structural design, and how it is calculated. We will also provide some examples of load width calculations in [residential structural design](https://clearcalcs.com/blog/what-is-load-and-tributary-width-in-structural-design-an-overview).

## What are Load Width, Tributary Width, and Tributary Area?

**Load width** refers to the actual width of a load that is applied on a structure. For example, if you have a beam that is supporting a load, the load width would be the actual width of the object that is being supported by the [beam](https://clearcalcs.com/calculations/us/analysis). In other words, load width is the physical dimension of the load itself.

**Tributary width**, on the other hand, refers to the width of the area on a structure that is supported by a particular element, such as a [beam](https://clearcalcs.com/calculations/us/timberBeamASD) or a [column](https://clearcalcs.com/calculations/us/timberColumnASD). 

For example, if you have a beam that is supporting a floor or a roof, the tributary width would be the width of the area of the floor or roof that is supported by the beam. In other words, tributary width is the area on a structure that is influenced by a particular element or load.

To illustrate this difference further, let's say you have a wall that is supporting a roof. The load width of the roof would be the actual width of the roof, while the tributary width of the wall would be the width of the area of the roof that is directly supported by the wall. This information is important in structural analysis and design, as it helps determine the loads that a particular element or member of the structure will need to support.

**Tributary area** refers to the total area of the structure that is supported by a particular load. Loads can be either point loads or distributed loads. Point loads are loads that are applied to a specific point on a structure, while distributed loads are loads that are spread out over an area. 

Load width and tributary width are not the same things, but they are related. The load width determines the tributary width, which in turn determines the tributary area.

### Why is Load Width & Tributary Area Important in Structural Design?

Load width is important in structural design because it helps engineers and architects determine the load-bearing capacity of a structure. By calculating the tributary area, they can determine how much weight a particular part of the structure needs to be able to support. 

Engineers can streamline the design process by finding the critical tributary area for a member (e.g., a primary beam), which is the largest area supported by the member and, consequently, the highest loading applied to the member. 

Once the primary beam is sized to have sufficient capacity for the critical tributary area loading, then this size beam can be used for all primary beams in the structure, which allows for efficiency in design and economies of scale through procurement. 

By using this design procedure, only one set of calculations needs to be performed for each different type of member throughout the whole structure, rather than individually calculating the loading and capacity of every single member. 

From the below diagram, the critical tributary area for the beams is CD2-2, so once this loading is calculated and the beam is sized, this beam size can be used for all other beams in the structure. 

Similarly, based on the below diagram, the critical tributary area for the columns is B3, so once this loading is calculated and the column is sized, this column size can be used for all other columns in the structure.

![An illustration of floor plan showing tributary width of beams and columns](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_width_example_05a0680bd5.jpg)
_Figure 1: An example of tributary area for columns and beams ([Reference](https://mocivilengineering.com/tributary-arealoading/))_

### How is tributary width calculated?

To calculate the tributary width for a distributed load, **the area of the load is divided by the distance between the supporting columns or walls**. 

For example, if a roof has a distributed load of 20 kN per square meter and is supported by two walls that are 20 meters apart, the tributary width of the walls is 10 meters. The load per linear meter would be 200 kN/m, which is the total load of 20 kN/m^2 multiplied by the tributary width of 10 meters.

For concentrated loads, the tributary width is the distance from the center of the load to the nearest supporting column or wall. 

For example, if a column is placed 5 meters from a supporting wall and has a load of 10 kN, the tributary width of the column would be 5 meters. The load per linear foot would be 2 kN/m, which is the total load of 10 kN divided by the tributary width of 5 meters.

## Applications of Tributary Width

It is more conservative to use tributary width than point loads for bending but not shear. 

When calculating the bending moment of a structural member, the load is distributed across the tributary width rather than concentrated at a single point. 

This is because the bending moment is a function of the load distribution across the beam, and the moment is greater at points where the load is concentrated. 

Therefore, using tributary width for bending calculations is a more conservative approach since it results in a higher calculated bending moment than using point loads, as shown below. This means that the calculated bending stress will also be higher, which can result in a larger beam size or a more conservative design.

![An illustration showing load distribution across a beam](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_width_bending_57180bc241.png)
![An illustration showing total beam length](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_width_bending_length_448a888819.png)
![A diagram of bending moment against beam length](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_width_bending_diagram_719d6201c5.png)
_Figure 2: Tributary widths are conservative for bending_

On the other hand, when calculating shear in a structural member, the load is distributed uniformly across the member's cross-section, regardless of whether the load is concentrated or distributed. 

Therefore, the use of tributary width or point loads does not have a significant impact on the calculated shear. As a result, it is more common to use point loads for shear calculations since it simplifies the analysis without significantly affecting the results.

When designing a cantilever member, the tributary width method may not be conservative since it assumes that the entire load is distributed to the support at the end of the member. However, for a cantilever, the load is not distributed uniformly along the length of the member, and the portion of the cantilever beyond the support does not contribute to the load-carrying capacity of the support. 

Therefore, in the case of cantilevered members, using the tributary width method can result in a lower calculated bending moment and may lead to an under-designed structure.

For continuous members, the tributary width method can also lead to non-conservative results because it assumes that each support carries only the load tributary to it. In reality, the load distribution across a continuous member is more complex and may result in load sharing between supports. This can result in a situation where a particular support is carrying a load greater than what is calculated using the tributary width method, leading to potential structural issues.

In residential projects, the use of incorrect load calculations can lead to a structure that is not strong enough to support its intended loads, which can result in safety issues and building failures. 

Therefore, it is crucial for structural engineers to carefully consider the load distribution and use appropriate analysis methods to ensure that the structure is adequately designed for its intended use. 

In the case of cantilevered members and continuous members, using more advanced analysis methods, such as finite element analysis or moment distribution analysis, may be necessary to accurately determine the load distribution and ensure the structure's safety and stability.

Fortunately, shear is not critical in residential timber and steel construction, and cantilevered & continuous members are less common, so tributary width is usually conservative and applicable for residential design. 

## Examples of Tributary Width Calculations in Residential Structural Design

### Roof Tributary Width & Tributary Area on Columns

Let's take the example of a rectangular room with dimensions of 7 meters by 4 meters, and a flat roof supported by three primary beams and four columns placed at the corners of the room. The ceiling and floor have a weight of 3 kN/m^2 as per the below diagram.

![A diagram showing a rectangular room with beams and columns ](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_width_residential_example_4055ff7df6.png)
_Figure 3: An example of a simple residential structure_

The tributary width of each column supporting the roof will be half the distance to the adjacent columns, as the load on the roof is evenly distributed. 

Therefore, the roof tributary area on the columns will be 3.5 meters (half the distance between columns along the width of the room) by 2 meters (half the distance between columns along the length of the room), which is 7 square meters. Therefore the load on the corner columns will be 7 square meters by the roof load of 3 kN/m^2 which is 21 kN.

### Roof Tributary Width & Tributary Area on Beams

Using a similar example above, the tributary width is half of the spacing between the vertical beams. Given the structural arrangement in the above diagram, the loads on the beams B1, B2, and B3 can be calculated as per the below.

For Beam B2, the tributary width will be 3.5 meters, giving a tributary area of 14 square meters when the tributary width is applied across the 4-meter length of the beam. The load on Beam B2 is found by multiplying the applied roof load of 3kPa by the tributary width of 3.5m, which gives 10.5 kN/m.

Beam B1’s tributary width is 1.75 meters which is half of the spacing between the vertical beams and is the same as Beam B3 (edge beam). The load on Beam B1 is found by multiplying the applied roof load of 3kPa by the tributary width of 1.75m, which gives 5.25 kN/m.

When calculating the loads using ClearCalcs templates, the tributary width should be inputted into ClearCalcs as shown below. 

![An image showing distributed loads input in ClearCalcs](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_width_input_Clear_Calcs_749aa72513.png)
_Figure 4: The input for tributary width in ClearCalcs ([Reference](https://support.clearcalcs.com/article/170-what-is-tributary-width))_

### Roof Tributary Width & Tributary Area on Skewed Beams

The tributary width can also be calculated for skewed beams. Let’s take the below example of the top-right skewed primary beam where a uniform load of 10 kN per square meter is applied to the entire floor.

![A diagram showing a structure with skewed beam](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_width_skewed_beam_afe01062c2.png)
_Figure 5: An example of a structure with skewed beams_

First, the length of the beam is calculated below:

L=√(6^2+4^2=7.21m)

Left end load=10 kN/m^2*4.5m=45 kN/m 

Right end load=10 kN/m^2*2.5m=25 kN/m

This can be inputted into ClearCalcs as per Figure 5 below.

![An image showing input for tributary widths in ClearCalcs](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_width_input_Clear_Calcs_skewed_beams_a6b4d5e8a0.png)
_Figure 6: How to enter tributary widths for skewed beams in ClearCalcs_

ClearCalcs can even perform these calculations for us by providing an easy way to enter area loads by providing four dimensions and the area load as per the below example that shows the inputs.
- Start Location (x_s) - area loading may start at any point along the beam (e.g., only applied on one span)
- End Location (x_e)
- Start Load Width (TW_s) - may be different than TW_e, as shown in Figure 6
- End Load Width (TW_e)
- Load Magnitude / Area Load (w)

![An image showing 3D view of a load area](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_area_3_D_view_6e1ba46958.png)
![An image showing plan and elevation view of load area](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_area_plan_elevation_c9ebc5862d.png)
![An image showing tributary width input in ClearCalcs](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_width_input_Clear_Calcs_easy_to_use_4f999c4db8.png)
_Figure 7: Tributary widths can be transferred into distributed loads using ClearCalcs ([Reference](https://support.clearcalcs.com/article/170-what-is-tributary-width))_

### Roof Tributary Width & Tributary Area on Split Beams

The tributary width can also be calculated for split beams. 

Let’s take the below example of the bottom horizontal split primary beam where a uniform load of 10 kN per square meter is applied to the entire floor.

![A diagram showing an example of a structural plan with split beams](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_load_width_split_beams_9999c4742f.png)
_Figure 8: An example of a stucture with split beams_

Left end and middle load=10 kN/m^2*(4.5m+2.5m)=65 kN/m
Right end load=10 kN/m^2*(2.5m+2m)=45 kN/m

Be sure to watch our residential structural expert, Laurent Gérin’s [Load & Tributary Width Webinar](https://www2.clearcalcs.com/videos/load-tributary-width) which shows more examples of how to easily calculate a broad range of tributary and load widths you may encounter on your projects and how then to use the incredibly flexible load entry tools in ClearCalcs to ensure you get a great design quickly.
 
## Conclusion

Load tributary width is an essential concept in structural design that helps engineers and architects determine the load-bearing capacity of a structure. 

By calculating the tributary area, they can ensure the safety and stability of a structure, especially in residential structural design. Aspiring engineers and designers must familiarize themselves with these concepts to create stable, safe and efficient structures. The design process can be streamlined when the largest tributary area is used to design members that can be used across the whole structure. 

It is important to note that load width calculations can vary depending on the type of load, and it is critical to follow the appropriate standards and codes when conducting load width calculations. 


In this article, we will explore what load tributary width is, why it is important in structural design, and how it is calculated. We will also provide examples of load width calculations in residential structural design.

Load and Tributary Width in Structural Design: An Overview

An image showing house foundations by shank_ali from Canva

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Structural foundation design is essential to any residential construction project, as it provides the base on which the entire structure rests. 

In general, the foundation is responsible for transferring the weight and loads from the building to the ground, making it a critical aspect of the overall stability and safety of the structure (Rao, 2010). 

The foundation design process involves several steps, beginning with soil investigation to determine the soil properties and site conditions. This information is critical as it helps the engineer determine the type of foundation suitable for the structure and the depth required to support the loads. The engineer considers factors such as [soil-bearing capacity](https://support.clearcalcs.com/article/158-bearing-capacity-calculator), soil type, groundwater conditions, and [seismic activity in the area](https://clearcalcs.com/blog/seismic-load-asce-7-16) to design a stable and secure foundation. 

Different types of foundations are used in residential construction, including shallow and deep foundations. 
- **Shallow foundations** are suitable for structures with low loads and are typically used for small buildings such as residential homes. 
- In contrast, **deep foundations** are used for structures with higher loads and designed to reach deep into the ground to provide the necessary support. 

In addition to the type of foundation, other critical design considerations include the size and shape of the foundation and the type of soil beneath it. 

It is also crucial to consider the impact of the surrounding environment, including factors such as temperature changes and moisture content, which can affect the foundation's stability over time. 

A poorly designed foundation can lead to a range of problems, including foundation settling, cracking, and even structural failure. Therefore, it is essential to accurately analyze and design foundations to ensure their capabilities in withstanding external loads and maintaining structural stability. 

This article gives an overview of foundation design in residential projects and highlights some critical design considerations.

## What is Structural Foundation?

A foundation is a structural component responsible for supporting and transferring the loads from the building to the ground. Foundation plays a critical role in ensuring the stability and safety of the building. In general, the foundation must be designed to withstand the loads imposed on it by the structure, such as the weight of the building, the occupants, and any additional loads like furniture or snow.

### The Role of Foundations in Residential Structures

In residential structures, the foundations serve as the base on which the entire structure rests. They support the entire weight of the building, ensuring it remains stable and safe for occupants while protecting the building against external forces like wind and seismic activity and insulating against moisture, preventing water from entering the building and causing damage. 

Additionally, foundations distribute the weight of the building evenly across the soil or rock, preventing localized stress and ensuring the building remains level. 

### What Does Foundation Design Entail, and Who is Involved in the Process?

Indeed, foundation design is an essential stage of any construction project, and it involves a thorough analysis of the soil and other site-specific factors to determine the appropriate foundation type and design that will provide adequate support for the structure. 

The foundation design entails several critical steps, including soil investigation, foundation type selection, design calculations, and construction specifications. 

This process starts with a geotechnical investigation to determine the soil characteristics and conditions of the site, such as soil type, bearing capacity, water table level, and potential for soil settlement or liquefaction (Som & Das, 2003). 

Based on the site's geotechnical report, the foundation engineer or geotechnical engineer selects the appropriate foundation type. 

Once the foundation type is selected, the foundation engineer performs design calculations to determine the required dimensions, reinforcement, and strength of the foundation elements. These calculations consider various factors, such as the weight of the building, the soil-bearing capacity, and the potential for soil settlement or uplift. 

The engineer also prepares construction specifications and drawings that provide detailed instructions for the contractor on how to build the foundation and what measures to take while constructing it. 

The foundation design process generally involves various professionals and experts, as outlined in Table 1, including structural engineers, geotechnical engineers, architects, and contractors. These professionals work together to ensure that the foundation meets the project's specific needs, including the required size, shape, and load-bearing capacity.

#### Structural Engineers

Structural engineers are responsible for designing the structural components of the foundation, including the footings, foundation walls, and other load-bearing elements. They work closely with architects to ensure that the foundation is designed to support the weight of the building and any anticipated loads, such as wind and seismic forces. They also ensure that the foundation is structurally sound and meets local building codes and regulations.

#### Geotechnical Engineers

Geotechnical engineers study the soil and geology of the building site to determine the appropriate foundation design. They perform soil tests, analyze the results, and provide recommendations for foundation types and depths. They also evaluate the site's slope stability and potential for landslides or other natural hazards.

#### Architects

[Architects design the overall layout](https://clearcalcs.com/blog/structural-design-for-residential-architects-how-to-get-started) and aesthetics of the building, including the size and shape of the foundation. They work with structural and geotechnical engineers to ensure that the foundation design supports the architectural vision of the building while meeting safety and structural requirements.

#### Contractors

Contractors are responsible for constructing the foundation based on the designs provided by the engineers and architects. They prepare the site, excavate the foundation, pour the concrete, and install any necessary reinforcing materials. They must follow the building plans and ensure that the foundation is constructed to the required standards and specifications.

## What are Design Considerations for Foundations?

Several design considerations must be taken into account when designing a foundation. Critical considerations include foundation type, depth, soil bearing capacity, soil type, frost protection, foundation materials, and load transfer.

### Foundation Types

Foundation types vary depending on different factors, including the type of soil on the building site, the region's climate, the building's weight, and the local building codes and regulations. Indeed, it is important to choose the right foundation type to ensure the stability and safety of the building. The following section describes some of the common foundation types.

#### Isolated footing (spread footing)

![An illustration depicting the structure of an isolated footing](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_foundation_overview_isolated_footing_6d72f92ee3.png)
_Figure 1: Isolated footing (spread footing)_

It is a type of foundation used to support a single column or post. It is typically a [concrete pad](https://clearcalcs.com/calculations/us/foundationsSpreadFootingUSA) poured at the base of the column, which spreads the load over a larger area of soil.

#### Strip foundation (combined footing)

![An illustration depicting the structure of an strip foundation (continuous footing)](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_foundation_overview_strip_foundation_fb2a034a79.png)
_Figure 2: Strip foundation (continuous footing)_

It is a type of foundation used to support a load-bearing wall. It is a long, narrow concrete strip that runs along the length of the wall and spreads the load over a larger area of soil. Strip footings are used for buildings with multiple stories.

#### Raft foundation (mat foundation)

![An illustration depicting the structure of a raft or mat foundation](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_foundation_overview_raft_mat_foundation_16865b920a.png)
_Figure 3: Raft foundation (mat foundation)_

It is a type of foundation used to support an entire building. It is a large, flat concrete slab that extends over the entire footprint of the building, distributing the load over a larger area of soil. Raft footings are used for buildings constructed on weak or unstable soil. The main difference between strip and raft foundations is that the strip foundation efficiently utilizes limited space for individual footings, providing a balanced load distribution for closely spaced columns.

#### Pile foundation

![An illustration depicting the structure of a pile foundation](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_foundation_overview_pile_foundation_0ab928f1f4.png)
_Figure 4: Pile foundation_

It is a deep foundation used when the soil is too weak to support the weight of the building. It involves driving piles into the soil to transfer the load of the building to deeper, stronger layers of soil.

### Foundation Load Transfer

[Load transfer is the process of transferring the loads from the building to the foundation](https://support.clearcalcs.com/article/24-linking-reactions-between-beams-and-columns-load-path-tracking). Generally, the foundation must be designed to transfer the loads to the soil safely. The loads imposed on the foundation include dead loads, such as the weight of the building, and live loads, such as the occupants' weight and furniture. 

The mechanism of distributing the building load on soil depends on the type of foundation used. 

Nevertheless, in all cases, the building load is distributed to the soil through a mechanism known as bearing capacity (it is the ability of the soil to support the weight of the building without excessive settlement or movement). The load from the building is transferred to the footing slab, Figure 1, which is a wide and thick part of the foundation that spreads the load over a large soil area (Das & Sivakugan, 2018). The foundation then distributes the load to the soil beneath it, which supports the weight of the building. 

The distribution of load to the soil is based on the principles of soil mechanics. The soil's load-bearing capacity depends on several factors, such as the type and strength of the soil, the depth of the footing, and the width of the footing. 

To ensure that the load is distributed evenly, the footing is designed to be wider than the building's walls or columns. The width and depth of the footing are determined by the soil's load-bearing capacity and the building's weight. During construction, the footing is placed on a compacted layer of soil and reinforced with steel bars or mesh to increase its strength.

![An illustration showing load path in buildings from EngineersDaily, 2014](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_foundation_overview_load_paths_foundations_28d367e2f7.png)
_Figure 5: Load path in buildings ([Reference](https://www.engineersdaily.com/2014/05/how-loads-flow-through-building.html))_

### Foundation Depth

The depth of the foundation is one of the most critical design considerations. It depends on the type of soil and the loads that will be imposed on the foundation. 

For instance, a building located in an area with poor soil conditions will require a deeper foundation to provide adequate support. The foundation's depth also depends on the frost depth in the area, which varies depending on the location. For example, a shallow foundation may be sufficient in shallow frost depths. In contrast, a deeper foundation may be required to prevent frost heave in areas with a deep frost depth.

### Soil Bearing Capacity

Soil bearing capacity refers to the maximum load the soil can withstand without failure. 

It is essential to determine the soil's bearing capacity to design a foundation that can withstand the loads imposed on it (Das, 2021). Several factors influence the soil's bearing capacity, such as soil type, moisture content, and compaction. A geotechnical engineer can conduct a soil test to determine the soil's bearing capacity and recommend an appropriate foundation design.

### Soil Type

The soil type on the construction site plays a crucial role in foundation design. Different types of soil have varying bearing capacities and compaction properties. 

Besides, some soil types are more susceptible to swelling or shrinking, which can cause significant damage to the foundation and the structure. For example, expansive soils are known to swell, causing foundation movement and structural damage. Accordingly, understanding the soil's characteristics is essential to design a foundation that can withstand the soil's properties.

### Frost Protection

Frost heave can cause significant damage to the foundation and the structure. Hence, designing the foundation with adequate frost protection is essential to prevent the soil from freezing and heaving. 

Generally, insulation helps to prevent the soil from freezing and heaving, while footing depth ensures that the foundation is located below the frost line to prevent frost heave. Therefore, selecting adequate insulation and footing depth are critical factors in providing frost protection for the foundation.

### Foundation Materials

Several types of foundation materials can be used in residential construction. Among them, reinforced concrete is the most widely used option in residential structures thanks to its high durability and low cost. The choice of material depends on several factors, such as the soil type, load, and structure's design. 

## Summary
In conclusion, the foundation of a residential structure is a critical aspect of its construction and structural integrity. 

The foundation supports and transfers loads from the building to the ground, ensuring stability and safety for its occupants. The design process involves a qualified structural engineer who considers several factors, including soil investigation, load analysis, and design calculations, to determine the foundation's type, size, and shape. 

Critical design considerations include foundation depth, soil bearing capacity, soil type, frost protection, foundation materials, and load transfer. A poorly designed foundation can lead to problems like foundation settling, cracking, and even structural failure. 

Therefore, it is crucial to work with a qualified engineer to ensure that the foundation is designed to withstand the loads and maintain the structure's stability and safety.

#### References
- Das, B. M., 2021. Principles of geotechnical engineering. s.l.:Cengage learning.
- Das, B. M. & Sivakugan, N., 2018. Principles of foundation engineering. s.l.:Cengage learning.
- EngineersDaily, 2014. How Loads Flow Through a Building?. [[Online]](https://www.engineersdaily.com/2014/05/how-loads-flow-through-building.html)
- Rao, N. K., 2010. Foundation design: theory and practice. [[Online](https://www.academia.edu/39834717/Foundation_Design_Theory_and_Practice_N_S_V_Kamesware_Rao)].
- Som, M. N. & Das, S. C., 2003. Theory and practice of foundation design. s.l.:PHI Learning Pvt. Ltd.


This article gives an overview of foundation design in residential projects and highlights some critical design considerations.

Structural Foundations Design in Residential Projects: An Overview and Design Considerations

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Structural design in the United States has long been governed by a complex patchwork of codes and standards, some of which are standardized nationwide and some of which are amended to varying degrees by individual states. 

In ClearCalcs, we support the usage of several recent revisions of the [International Building Code (IBC)](https://www.iccsafe.org/products-and-services/i-codes/2018-i-codes/ibc), [International Residential Code (IRC)](https://www.iccsafe.org/products-and-services/i-codes/2018-i-codes/irc/), and [ASCE 7](https://www.asce.org/publications-and-news/asce-7), as well as a couple of individual states' modifications where there are particularly significant structural amendments (such as the California Building Code (CBC) in California). 

In this blog post we'll examine building codes from different levels of governments and institutions in detail - including their purpose, scope & requirements - so as to help you understand why they're so important for successful structural design projects across the US. 

We'll also discuss what it means to be designing under a particular code and the aspects of your design that are and are not affected in ClearCalcs. 

## The Legally Required Code

The building code governing your design is legally proscribed by legislation adopted independently in each individual state. In the US, all 50 states have adopted codes that are based upon the same 'model legislation', in the form of the International Building Code (IBC) and/or the International Residential Code (IRC). 

![[BLOG] building-code-ibc-irc.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_building_code_ibc_irc_91552547e5.png)
_Figure 1: The International Building Code (IBC) ad the International Residential Code (IRC) published by the [International Code Council (ICC)](https://www.iccsafe.org/)_

Those codes are related the entire construction of a building, including not just structural design, but also architectural design, fire design, accessibility, etc. 

In most cases, when states have amended the IBC or IRC, they've amended only or primarily those latter sections and generally have not modified the structural design meaningfully. 

In most states, therefore, you can accurately perform your structural design using the basic IBC or IRC. The code versions in current use by each state may be viewed for the International Building Code [here](iccsafe.org/adoptions/code-adoption-map/IBC) and for the International Residential Code [here](https://www.iccsafe.org/adoptions/code-adoption-map/IRC). The actual amended text for each state is also viewable in building code management software such as [UpCodes](https://up.codes/).

Note also that certain larger commercial or industrial structures sometimes make use of a clause in the IBC that allows for the ASCE 7 standard to be used in lieu of most of the IBC's load calculations, and ClearCalcs therefore additionally offers a couple revisions of ASCE 7 as a 'building code' option as well.

## Material Design Standards

While the IBC and IRC are the governing legislation, those building code documents are not self-contained and do not define every step of the structural design themselves. 

They generally define the loads that should be applied and the load combinations that should be used, but they do not define how to calculate the strength capacity of all the different materials - wood, steel, concrete, etc. 

Instead, they refer out to standards developed by various industry bodies, such as the [American Wood Council (AWC)](https://awc.org/)'s [National Design Specifications (NDS) for Wood Construction](lhttps://awc.org/publications/2018-nds/) for wood, [American Institute for Steel Construction (AISC)](https://www.aisc.org/) [ 360 Specification for Structural Steel Buildings](https://www.aisc.org/publications/steel-standards/aisc-360/) for steel, or [American Concrete Institute (ACI)](https://www.concrete.org/) [318 Building Code Requirements for Structural Concrete and Commentary](https://www.concrete.org/store/productdetail.aspx) for concrete.

In ClearCalcs, when you select a building code to use, we'll change the load combinations to reflect the building code you want to use, but we will still use the most recent revision of the relevant material standard. We do not currently match material standard revisions to building code revisions. Most states explicitly allow you to use newer revisions of the material design standards, but please check with your individual state to ensure that this is the case.

Specifically for the IRC and its local state variants, note that wood design has different methodologies allowed. You may either use the prescriptive span tables in the IRC document itself, or the IRC alternatively allows you to use the NDS - which is what ClearCalcs does. 

We do not use those prescriptive span tables in the IRC document, as they are much more restrictive and generally more conservative (they have no provision for [custom cross-sections](https://support.clearcalcs.com/article/135-how-to-use-the-custom-cross-section-calculator), and generally do not meaningfully account for complex loading scenarios or multi-span support conditions). 

Unfortunately, the IRC does not provide such an alternative design pathway for cold-formed steel or concrete; you must use the IRC's prescriptive span table methods for CFS or concrete, and ClearCalcs does not yet support this. 

Therefore, if you do wish to design using the IRC, you may only do so for the wooden portions of your building.

## Notable State Variations 

A couple of states do make notable modifications to the structural design portions of the building codes.

One of these is California, where there are numerous additional clauses for detailing and design largely as a result of earthquake requirements. However, California also defines the need to abide by its various amendments based upon the type of building being designed and thereby the relevant government agency. 

Buildings under the purview of the Office of Statewide Health Planning and Development (most medical buildings) or the Division of the State Architect - Structural Safety (mostly schools) are particularly stringent in added clause requirements, and ClearCalcs does not include support for all the numerous amendments relevant for these buildings. 

ClearCalcs does, however, support the California amendments for Department of Housing and Community Development (grade 1) buildings, also known as HCD-1 buildings. However, even in the HCD-1 amendments, California also notably amends the concrete material design standard specifically. ClearCalcs now fully supports the latest California Building Code including the concrete amendments.

![An image showing ClearCalcs structural design software with support for the latest California Building Code 2022](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_building_code_clearcalcs_project_default_cbc_23e6c9451e.png)
_Figure 2: ClearCalcs structural design software fully supports the latest California Building Code (CBC) 2022 including the concrete amendments_

## Conclusion

Thus, we can see that building codes and load combinations are integral components when designing buildings in the United States. While a majority of states follow the same model legislation from IBC and/or IRC, there are a handful of states with notable modifications that need to be taken into consideration. 

Understanding the differences between codes used at an individual state level will ensure a safe and successful outcome for any construction project.  

An effective way to manage building codes is to utilize structural design tools like ClearCalcs to guarantee accuracy. All code information is integrated into the platform for easy access, so you don’t have to waste time searching for various specific codes or enforcing conflicting requirements from different states. The results obtained with this software offer quick answers to keep projects running on time and within budget restrictions. 

Do yourself a favor, save time by researching once and share insights instantly with all your projects thanks to ClearCalcs. Don't miss out on this powerful tool - try ClearCalcs for free today and experience how it simplifies complex structural calculations!


Building codes are essential for ensuring the safety and quality of construction projects. This blog post will discuss what building codes are, why they're important, and how to use them with respect to structural design in the United States.

Understanding Building Codes & Load Combinations in the United States

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This article provides an example of seismic load calculation of the residential building to the [ASCE 7-16](https://sp360.asce.org/PersonifyEbusiness/Merchandise/Product-Details/productId/233133882).

The building is assumed to be located in Bridgeville, California, with a reinforced concrete moment-resisting frame with 3 storeys and a total height of 29.53 ft.  

![An illustration showing a building height and weight in Imperial system](https://clearcalcs-prod2-cms.s3.amazonaws.com/BLOG_seismic_analysis_example_building_9f2cdd14d1.png)
_Figure 1: An example of a residential building for seismic load calculation using the ASCE 7-16 procedure_

The detailed calculation of the seismic loads is performed according to the specification of ASCE 7-16 ([check out the article for detailed outline of the procedures for calculating seismic loads in residential buildings using the linear static approach in Chapters 11 and 12 of the ASCE 7-16](https://clearcalcs.com/blog/seismic-load-asce-7-16)).

## Step 1: Identifying Site Class and Spectral Parameters
Using the [ASCE 7 Hazard Tool](https://asce7hazardtool.online/), we specified the building's location, a risk category II as default for residential buildings and a site class C to obtain the spectral parameters, S&#8347; value of 2.29g, S&#8321; value of 0.869g, and a long period T&#8343; of 8s. 

The building has a natural period, T, of 0.187s.

![Spectral Parameters and Site Class values from ASCE 7 Hazard Tool](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_example_step_1_e55b05f9b7.png)

## Step 2: Defining the Seismic Ground Motion Values

Once the spectral parameters for the building's site are obtained, the site coefficients (Fₐ and Fᵥ) are defined using the data provided in Table 11.4-1 and Table 11.4-2 in ASCE 7-16.

![Site coefficient Fa and Fv values](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_example_step_2_811929b3cf.png)

Thereafter, the design response spectrum is developed using the following equations: 

![An image showing MCE Spectral Response and Design Spectral Response Acceleration values](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_example_step_2_3_d6d12bff07.png)

## Step 3: Obtaining the Seismic Force Resisting System (SFRS) Properties

Once the design spectrum is established, the response modification coefficient, R based on the type of seismic resisting system and the material used, importance factor (I&#8495;), and approximate period parameters C&#8348; and C&#8339; are obtained from Table 12.2-1, 1.5-2, and 12-.8-2 respectively  in ASCE 7-16.

![An image showing values for Response Modification Factor, Importance Factor and Coefficient Ct and x.](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_example_step_3_d979589b01.png)

## Step 4: Calculating Seismic Response Coefficients

Thereafter, the seismic response coefficient is calculated and checked against the required conditions.

![An image showing the values of Seismic Response Coefficients](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_example_step_4_79f5f63d73.png)

## Step 5: Calculating the Effective Seismic Weight on the Building and Seismic Base Shear

Finally, the seismic base shear of the structure in the direction of concern is calculated and distributed to each story.

![An image showing Seismic Base Shear value](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_example_step_5_bb1bcee14f.png)
Once the parameters are obtained and set, the effective seismic weight of each story in the residential building is calculated based on the self-weight of the structural and non-structural elements and the partial contribution of the live load in the building (Figure 2).

![An image showing values of vertical distribution of seismic forces](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_example_vertical_distributio_of_seismic_forces_864bda1cf1.png)
_Table 1. Vertical distribution of seismic forces calculated using Eqs. 12.8-11 and 12.8-12 in the ASCE 7-16)_

![A diagram showing vertical distribution of seismic forces for the given example as per the ASCE 7-16](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_example_seismic_forces_ca01d9d085.png)
_Figure 2: Vertical distribution of seismic forces for the given example as per the ASCE 7-16_

### Conclusion

In order to comply with ASCE 7-16 requirements for analyzing seismic loads in residential buildings, engineers must follow the procedure outlined in Chapters 11 and 12. To find out how ClearCalcs integrates these calculations for seismic load analysis, check out our [Seismic Analysis Calculator to ASCE 7-16](https://clearcalcs.com/calculations/us/seismicAnalysisUS).

### Ready to start calculating in ClearCalcs?

[You can use the account for 14 days for free](https://clearcalcs.com/signup), with no commitment required. Need ClearCalcs for a one-off project? Subscribe to our month-to-month plan and cancel anytime, no questions asked.

This article provides an example of seismic load calculation of the residential building to the ASCE 7-16.

Practical Analysis of Seismic Load Using the ASCE 7-16

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Roof trusses can be used in a variety of roof shapes, including gable, hip, flat, and gambrel roofs. Roof trusses are becoming increasingly popular in residential home design due to their versatility, strength, and cost-effectiveness. 

In this blog post, we look at the different types of residential roof trusses and their advantages for various applications in residential design. 

## Common Types of Roof Trusses

### King Post Roof Truss

King Post Roof Trusses are simple designs consisting of a central vertical post, two sloping rafters,  two sloping struts and a horizontal tie beam. 

In a king post roof truss, the load path starts with the weight of the roof being transferred to the top of the two sloping rafters. These rafters are then supported by the central vertical post, which is typically located directly under the peak of the roof. The weight is then transferred down the king post to the two sloping struts on either side. These struts are angled and extend outward from the king post to meet the horizontal tie beam, which spans between the ends of the struts. The horizontal tie beam then distributes the weight of the roof evenly across the two struts, which in turn transfer the load to the foundation or supporting walls. 

They are commonly used in small or medium-sized buildings with a span of up to 8 meters. King post trusses are symmetrical and relatively easily replicated and assembled in a straightforward manner. This simplicity reduces the potential for errors during construction and makes the truss easier to analyze using structural engineering software, which makes them one of the most cost-effective options. 

![Diagram showing components of a king roof truss](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_king_roof_6c3734395c.jpg)
_Figure 1.1: Components of a King Roof Truss ([Reference](https://civiconcepts.com/blog/king-post-truss.))_

![An image showing an example of King Post Roof Truss set up in residential building](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_king_roof_example_5341157724.jpg)
_Figure 1.2: An example of a King Post Roof Truss in a residential building ([Reference](lhttps://www.oakmasters.co.uk/blog/fit-king-7-oak-king-post-trusses-transform-your-home/))_

### Queen Post Roof Truss

Queen Post Roof Trusses are similar to King Post Trusses, but have two vertical posts that provide additional support for longer spans and can be more visually appealing. 

They are commonly used in larger buildings with a span of up to 12 meters. However, they are typically more expensive to manufacture and install than King Post Trusses due to the additional members and longer spans.

![A diagram showing components of a Queen Post Truss](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_queen_post_truss_99086f82f4.jpg)
_Figure 2.1: Components of a Queen Post Truss ([Reference](https://constructioncivilengineering.blogspot.com/2017/06/meaning-of-queen-post-roof-truss.html))_

![An image showing how a Queen Post Truss is built for a residential building](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_queen_post_truss_example_38d55092ec.jpg)
_Figure 2.2: An example of a Queen Post Roof Truss in a residential building ([Reference](https://www.vermonttimberworks.com/our-work/timber-trusses/queen-post-truss/))_

### Scissor Truss

Scissor Trusses are designed with sloping bottom chords that intersect at a central point, creating a scissor-like shape. Scissor trusses are characterized by their angled bottom chords, which cross each other in the shape of an "X" at the center of the truss. In contrast, other truss types such as common trusses or king post trusses, typically have horizontal bottom chords that do not cross each other. While it's true that some other types of trusses, such as raised heel trusses, may have angled bottom chords, they are not considered scissor trusses because the chords do not cross over each other in the center of the truss.

This design provides additional height and openness to the space below, allowing for open planned living or commercial spaces with a vaulted or cathedral ceiling. 

They are typically used for spans up to 12 meters, and their design and construction are typically more expensive than simpler trusses such as the King and Queen Post.

![A diagram showing common components of a scissor truss roof](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_scissor_truss_8e2d4d6e62.png)
_Figure 3,1: Components of a Scissor Truss ([Reference](https://eldoradotruss.com/truss-information/))_

![An image showing an example of scissor truss used in residential roof design](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_scissor_truss_example_c079d1f753.jpg)
_Figure 3.2: An example of a Scissor Truss used in residential roof construction ([Reference](https://ecobuilt.co.za/portfolio/exposed-scissor-trusses-for-new-cottage-roof/))_

### Attic Roof Truss

Attic Roof Trusses are a modified version of the king post truss design that includes a room-like space within the roof. 

This type of truss is ideal for creating additional living space or storage within a roof without needing an additional level or more land space. Attic roof trusses are designed to create additional living or storage space in the roof area. 

These trusses typically cost more than king and queen post trusses due to the additional complexity of their design, including the need for a floor and ceiling structure which results in additional materials.

![A diagram showing common components of an Attic Truss](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_attic_roof_truss_f113592916.jpg)
_Figure 4.1: Components of an Attic Roof Truss ([Reference](http://design.medeek.com/resources/trusses.html))_

![An image showing an example of Attic Truss](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_attic_roof_truss_example_0eeb7c6e0f.png)
_Figure 4.2: An example of an Attic Truss in residential roof construction ([Reference](https://www.washingtonpost.com/business/2019/03/19/heres-what-look-when-you-need-pre-fab-truss-your-new-home-that-will-accommodate-an-attic/))_

### Fink Roof Truss

Fink Roof Trusses consist of a network of triangles that distribute the load evenly across the structure, providing maximum strength and stability allowing for long spans that are often utilised in commercial buildings. 

Fink trusses are cost-effective, easy to install, and can span up to 30 meters. Notably, the fink truss design features the distinctive W-shape. They are relatively cost-effective due to their simple design and material efficiency.

![A diagram showing components of a Fink Truss](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_fink_truss_be09c3a00e.jpg)
_Figure 5.1: Components of a Fink Truss ([Reference](http://www.all-concrete-cement.com/residential-roof-truss-design.html))_

![An image showing an example of a Fink Truss used in residential construction](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_fink_truss_example_f8da470f18.jpg)
_Figure 5.1: An example of a Fink Truss used in residential construction ([Reference](https://leachtrusses.com.au/everything-you-need-to-know-about-timber-standard-fink-trusses/))_

## Truss Designs to Match Roof Type
Builders often have to match truss types used to the architect's requirements. The three main types of roofs in residential construction are hip, gable, and flat roofs.

![An illustration showing different roof types for residential buildings](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_residential_roof_types_dc3e461fc8.png)
_Figure 6: Different roof types for residential buildings ([Reference](https://www.researchgate.net/figure/4-Schematic-of-Hip-High-Gable-and-Flat-Roof-designs-Source-UNDP-2007-53_fig4_305163378))_

### Hip Truss
Hip Trusses are used in hip roofs, where all four sides of the roof slope down to the walls. 

Hip trusses are designed to support the weight of the roof and provide additional support for the corners of the building. Hip trusses are commonly used in residential and commercial buildings. 

They are complex design to design, which can make them more expensive than simple trusses, especially for larger spans.

![An image showing components of a hip truss](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_hip_truss_437118e5e3.jpg)
_Figure 7.1: Hip Truss Setout ([Reference](https://www.pinterest.com.au/pin/198791771022318444/))_

### Gable Truss

Gable Trusses are used in gable roofs, which consist of two sloping sides that meet at a center ridge. 

Gable trusses are designed to provide support for the weight of the roof and to transfer loads to the walls. They are one of the simplest truss designs, which makes them very cheap for smaller spans.

![A diagram showing common components of a Gable Truss](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_gable_truss_b4ccadf4c3.jpg)
_Figure 8.1: Components of a Gable Truss ([Reference](https://build.com.au/roof-framing-elements))_

![An image showing an example of a Gable Truss used in residential roof construction](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_gable_truss_example_c2f14887ec.jpg)
_Figure 8.2: An example of a Gable Truss used in residential roof construction ([Reference](https://leachtrusses.com.au/gable-timber-roof-trusses/))_

### Flat Truss
Flat Trusses are used in flat or low-pitched roofs often where there are building height limitations due to council regulations, overhanging trees or architectural requirements. 

They are designed to provide support for the weight of the roof and to distribute loads evenly across the structure. Flat trusses can be used for roofs in residential buildings or substituted for steel beams in composite concrete slab systems in commercial buildings, as shown in Figure 9.1. 

They are more complex to design and install than simple trusses, which can make them more expensive. When using flat trusses, a designer should consider how to adequately provide drainage, so water does not pool on the roof.

![Composite slab using Flat Trusses](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_flat_truss_composite_slab_cff0052808.jpg)
_Figure 9.1: Composite slab using Flat Trusses ([Reference](https://www.pinterest.com.au/pin/18436679704166950/))_

![An example of Flat Trusses used in construction](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_flat_truss_example_2a8ecfd752.jpg)
_Figure 9.2: An example of Flat Trusses system used in construction ([Reference](https://www.seattletimes.com/explore/at-home/for-flat-floors-and-open-designs-choose-wood-trusses-over-joists/))_

The internal chords of a flat truss can be arranged differently to be a Warren, Pratt, or Howe truss. 

#### Warren Truss

A warren truss is a type of truss with a series of equilateral triangles within the structure. This truss has diagonal members that alternate in direction and cross over each other in a zigzag pattern. It is commonly used in bridges and other structures that require a lightweight and efficient design. If large steel members are used the warren truss can be used in spans up to 250 feet (75 metres).

#### Pratt Truss

A Pratt truss is similar to the Warren truss in that it has diagonal members that alternate in direction, but it features vertical members as well. This truss is characterized by its vertical members that form the posts, and its diagonal members that slope towards the center of the span. The Pratt truss is commonly used in spans up to 250 feet (75 metres) where large steel members are used, and it is often used in bridges, industrial buildings, and other structures that require a strong and rigid design.

#### Howe Truss

A Howe truss is a type of truss with vertical members that form the posts, and diagonal members that slope away from the center of the span. This truss is characterized by its diagonal members that are under compression, and its vertical members that are under tension. The Howe truss is commonly used in spans up to 200 feet (60 metres), and it is often used in bridges, roofs, and other structures that require a strong and efficient design.

![Chord arrangements in Flat Trusses](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_flat_internal_chords_daf633b69d.png)
_Figure 9.3: Chord arrangements in Flat Trusses ([Reference](https://www.next.cc/journey/discovery/truss))_

### Mono Roof Truss

Mono Roof Trusses (also known as monopitch and skillion trusses) are similar to Fink trusses but are designed to span a greater distance with a shallower pitch which are often used in structures such as sheds, garages, and small workshops.

This design is commonly used in commercial and industrial buildings where a low-pitched single-sloping plane roof is desired due to building height limitations or architectural requirements. 

Their simple design makes them a cost-effective option for smaller spans, but they typically need additional reinforcement to make them structurally adequate for longer spans in comparison to king and queen post trusses.

A mono vaulted truss is a variation of the mono truss that has a raised or vaulted center section, creating a more open and spacious interior. The raised center section of the mono vaulted truss is achieved by extending the center portion of the top chord upwards, while maintaining the same angle of the bottom chords. This creates a peaked or arched shape in the center of the roof, which provides additional headroom and allows for larger windows or skylights. 

While the basic design of the two truss types is similar, the addition of the raised center section in the mono vaulted truss requires additional engineering and support to ensure that the roof structure can handle the additional weight and stress.

![A diagram showing different types of Mono Trusses](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_monon_trusses_755b3a3061.jpg)
_Figure 10.1: Different types of Mono Trusses ([Reference](https://www.menards.com/main/buying-guides/building-materials-buying-guides/roof-truss-buying-guide/c-19431.htm))_

![An image showing an example of Mono Truss](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_monon_trusses_example_8cf8c43d0a.jpg)
_Figure 10.2: An example of Mono Truss being used in residential roof design ([Reference](https://www.pinterest.com.au/pin/229754018464656454/))_

## Design Standards for Roof Trusses

In Australia and the United States, there are several design standards that must be followed when designing roof trusses. 

In the United States, the most common standard is [the National Design Specification for Wood Construction (NDS)](https://awc.org/publications/2018-nds/), which provides guidelines for the design and construction of wood structures, including roof trusses. 

In Australia, the most common standard is [the Australian Standard for Timber Structures (AS 1720)](https://www.standards.org.au/standards-catalogue/sa-snz/building/tm-010/as--1720-dot-1-2010), which provides guidelines for the design and construction of timber structures, and [the Australian Standard for Installation of nailplated timber rooftrusses (AS 4440)](https://www.standards.org.au/standards-catalogue/sa-snz/building/tm-010/as--4440-2004) which provides specifications and performance requirements and for the bracing, connection and installation of nailplated timber trusses. 

These standards are conveniently built into [ClearCalcs Truss Analysis Wizard](https://clearcalcs.com/calculations/us/trussAnalysis).

## Deciding Which Truss Type to Use

When deciding on what type of trusses to use for roof design, engineers must consider a variety of factors, including the shape and span of the roof, height restrictions, architectural requirements, ceiling type, material availability, and load applied. 

King Post and Queen Post trusses are commonly used in small to medium-sized buildings, while Scissor, Attic, Fink, and Mono trusses are used in larger and more complex buildings and are typically more expensive. 

Hip, Gable, and Flat trusses are used to meet architectural requirements for the shape of the roof. 

Additionally, engineers must consider procurement times and ease of installation. Prefabricated trusses are typically better quality (constructed by professionals), cheaper (reduction in onsite labor costs), and easier to install (fewer onsite connections) but procurement times can often be 1-6 months. 

If the lead times in your area for prefabricated trusses are too long, structural engineers can design trusses to be stick-built on-site. This involves cutting timber and assembling the necessary components on-site, using nail-plated connections. Stick-building trusses can be a time-consuming process, but they can be a cost-effective solution for smaller projects or projects with unique design requirements. 

[ClearCalcs Truss Analysis Wizard](https://clearcalcs.com/calculations/us/trussAnalysis) can be incredibly useful for trialing different truss types to determine what the most efficient design will be.

### Cost Ranking for Trusses

It's difficult to provide an exact ranking of trusses in terms of cost, as prices can vary depending on a variety of factors such as size, design complexity, location, and local market conditions. However, in general, the trusses listed above can be ranked from least expensive to most expensive as follows: including their maximum span in meters:

- Flat truss: Simplest and least expensive, with spans up to 6 meters.
- King post truss: Relatively simple and inexpensive, with spans up to 10 meters.
- Queen post truss: Slightly more complex than a king post truss, with spans up to 12 meters.
- Gable truss: Common and relatively simple, with spans up to 15 meters.
- Fink truss: Commonly used in residential and light commercial construction, with spans up to 25 meters.
- Attic truss: More complex truss designed to create additional living space in the attic, with spans up to 30 meters.
- Mono roof truss: Simple truss with a single sloping plane, with spans up to 35 meters.
- Hip truss: More complex truss with sloping rafters on all sides, typically used in larger buildings, with spans up to 45 meters.
- Scissor truss: More complex truss with angled bottom chords that cross over each other to create a vaulted or arched shape, with spans up to 50 meters.

Again, it's important to note that these maximum spans are general and can vary depending on a variety of factors such as truss design, building materials, and local building codes


In this blog post, we look at the different types of residential roof trusses and their advantages for various applications in residential design. 

Types of Roof Trusses and Their Applications in Residential Design

Steel trusses by jeffhochstrasser via Canva

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When it comes to residential structural design, trusses can offer a number of advantages for house framing applications. But what exactly is a truss, and how do they work? As structural engineers, architects, and other professionals in the industry know, understanding truss structures is key to successfully designing safe and strong houses.

This blog article provides an overview of trusses, explores their different types, explains how they work, and discusses their benefits and limitations when designing safe and secure frames for houses.

## What is a Truss?

A truss is a structural system made entirely of axially loaded members that consists of a collection of elements connected at pin joints or nodes.

The characteristics of a truss include the following:

- All straight members
- Members are connected together with pin joints
- Connected only at the ends of the members
- All external forces (loads & reactions) must be applied only at the joints

In theory, the pin joints provide no rotational resistance and behave as hinges.

### What are The Different Types of Trusses?

Trusses are either plane trusses or space trusses.

A plane truss is a truss where all members lie in a single plane. As a result, plane trusses are treated as two-dimensional systems. Plane trusses are commonly used in different structures globally.

Some examples of commonly known plane trusses such as Flat Warren Truss, Flat Howe Truss, Fink Roof Truss and Howe Roof Truss are illustrated in Figure 1 ([check out this article to find out more about the different types of trusses for residential structures](https://clearcalcs.com/blog/types-of-roof-trusses)).

![Common types of plane trusses](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_types_682c26b6d6.png)
_Figure 1: Some examples of common plane trusses ([Reference](https://support.clearcalcs.com/article/152-truss-types))_

Conversely, space trusses have members not limited to a single plane. This means that space trusses need to be analyzed as a three-dimensional system.

![An image illustrating space frames in three-dimensional format](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_space_frames_992d92e10a.jpg)
_Figure 2: An example of space truss frame ([Reference](https://www.cnxzlf.com/news/analysis-of-space-frame-structure-and-truss-structure/))_

### Truss Terminology

Common terminology relating to timber trusses is demonstrated from the below extract of Australian Standard AS 4440 (2004) - Installation of nail-plated timber roof trusses for residential and light commercial structures.

![A diagram of timber truss with common terms ](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_trusses_common_terms_950e5fd6b5.png)
_Figure 3: Common components and terminology of roof timber truss ([Reference](https://www.standards.org.au/standards-catalogue/sa-snz/building/tm-010/as--4440-2004))_

- **Timber Truss:** A framework constructed with timber of uniform thickness and fastened together in one plane by connectors such as metal nailplates, bolts, plywood gussets, or other similar devices.
- **Truss Overhang:** The portion of top chord extending beyond the body of the truss to provide eaves.
- **Eaves:** The portion of main building outside the external wall line. Generally, it includes the truss overhang and also cantilevered portions if present.
- **Truss Overhang:** The portion of top chord extending beyond the body of the truss to provide eaves.
- **Eaves:** The portion of main building outside the external wall line. Generally, it includes the truss overhang and also cantilevered portions if present.
- **Pitching Point:** The intersection of underside of top chord and underside of bottom chord.
- **Nailplates:** Metal plate connectors manufactured predominantly from light gauge galvanized steel with teeth spaced and formed within the parent metal. Nailplates are normally pressed into opposite faces of the timber members to form a spliced or gusseted type of joint.

## Truss Materials

Trusses are typically made out of timber and/or steel. Steel is used for longer-spanning trusses, particularly those in commercial buildings or bridges, while timber trusses are typically used in residential construction. [Sustainably sourced timber trusses are more ecologically friendly](https://pasquill.co.uk/are-roof-trusses-eco-friendly/).

![An image illustrating trusses made from timber and steel](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_materials_c7dc83fd07.jpg)
_Figure 4: Examples of timber and steel trusses ([Reference](https://freimans.com/metal-vs-timber-why-its-better-to-use-timber-trusses/))_

## Procurement and Cost of Trusses
Most roof trusses and all steel trusses are prefabricated and delivered to the site, which ensures quality workmanship and synergies from economies of scale. As a result, the lower amount of labor and plant required on-site greatly reduce construction costs. 

Typically, timber truss suppliers and steel fabricators need at least 4 weeks of lead time to manufacture and deliver trusses to the site.

Timber trusses are typically cheaper and have less strength but have shorter procurement times due to standard sizes and simpler workmanship.

The costs of timber trusses vary significantly. The variables can include where you purchase them or if you opt for prefabricated trusses vs. trusses built on-site. In Australia & the US, you can expect to pay anywhere from $200 to $700 USD per truss (note most homes will need several trusses, usually between 20 and 40 as a rough estimate). Timber roof trusses for your home will cost approximately $9,000 USD to $20,000 USD.

It can be difficult to accurately forecast the cost of timber trusses in Australia and the US as they vary widely depending on several factors, including the size and design of the trusses, the type of timber used, and local market conditions. Additionally, the cost can be calculated in different ways, such as per cubic metre or per tonne.

Steel trusses are more expensive usually due to the price of steel and more labour required to construct the connections (bolts or welds) compared to the nail plated connections of a timber truss.

Steel trusses are typically twice as expensive as timber trusses as they are typically bespoke designs but the price is heavily dependent on steel prices. 

[Steel Trusses Tech Australia](https://www.steeltrussestech.com.au/), [Aussteel](https://aussteel.net.au/) and [Australian Steel Framing](https://www.australiansteelframing.com.au/) are the most common steel truss suppliers in Australia while timber trusses can be sourced from [Timbertruss](https://www.timbertruss.com.au/) & [Australian Timber and Trusses](https://www.austt.com.au/). In the US, [Structural Timber Trusses](https://www.americanpoleandtimber.com/wood-timber-products/timber-trusses-and-corbels/structural-timber-trusses/) and [American Truss](http://www.atruss.com/) are long-time industry suppliers of timber trusses, while steel trusses can be sourced from [US Steel Truss](https://www.ussteeltruss.com/) and [Adams Truss](https://adamstruss.com/).

## Benefits of Truss System

The benefit of a truss is that the members are axially loaded, so there is no shear or bending. This means they are either in compression or tension or have no force (zero force members). This makes trusses a very efficient structural component.

Like any structure, a truss transmits externally applied forces through its elements and back into the supports or foundations of that structure. Because of the efficiency of their structural mechanics, trusses can span very large distances with relatively small section sizes. This lightweight nature of the member makes it quicker, easier, and ultimately cheaper to construct or install on-site. This efficiency makes them well suited in roofs in residential construction and bridges in civil infrastructure.

Trusses can span longer distances than beams or traditional frames, resulting in building projects that are less reliant on internal supporting structures such as load-bearing walls, beams, & columns. As a result, larger open spaces can be achieved by improving the aesthetics of a home. Buildings can also be future-proofed for different use cases, given there is fewer load-bearing walls and columns.

When there is fewer load bearing vertical members (walls and columns), there is more potential for future renovations to transform the existing structure into a building with a different use cases. For example, a building that uses trusses that have large spans to load bearing columns or walls on the perimeter of the property may only have non-load bearing walls internally. These walls can be demolished with ease and a residential structure could be transformed into a gymnasium, education center or any other type of building requiring large open spaces.

Trusses can also be prefabricated to minimize labor and plant on site reducing construction costs. The effectiveness of trusses is demonstrated by their frequent use to support long spans and heavy weights.

## Limitations of Trusses
Members of a truss are slender and not capable of supporting large lateral loads and usually need to be used in conjunction with steel wire or braced framing to provide lateral support as per [Figure 4.1 in AS 4440](https://www.standards.org.au/standards-catalogue/sa-snz/building/tm-010/as--4440-2004). 

![An example of bracing system for roof trusses](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_bracing_system_b752f0d14a.png)
_Figure 5: An example of bracing system for roof trusses ([Reference](https://www.standards.org.au/standards-catalogue/sa-snz/building/tm-010/as--4440-2004))_

Fortunately the lateral stability elements are simple to design and can be done so using ClearCalcs[ Truss Analysis](https://clearcalcs.com/calculations/au/trussAnalysis) and [Steel & CFS calculators](https://clearcalcs.com/calculations).

## Conclusion

To recap, trusses can be a cost-effective option in house framing design. By understanding their different types and materials, as well as their benefits and limitations; designers have a wide array of options when engineering trusses for frame structures.  

Trusses are a great option when the architect or builder is looking to have a horizontal member span over 8 meters. Trusses spanning up to 16 meters can be designed in accordance with the Australian Standard AS 4440 (2004), installation of nail-plated timber roof trusses for residential and light commercial structures.

However, trusses can be engineered to span much larger than 16 meters using Finite Element Analysis which is conveniently built into the [Truss Analysis Wizard calculator](https://clearcalcs.com/calculations/au/trussAnalysis). In addition, timber trusses can be preferable for spans smaller than 8 meters when steel prices are high.

### Ready to start calculating with ClearCalcs?

If you’re considering undertaking a project that includes house-framing using a truss system or are curious about what it means, ClearCalcs is available to help! Our [Truss Analysis Wizard](https://clearcalcs.com/calculations/au/trussAnalysis) makes frame design structurally sound without any calculations or guesswork involved - so you can rest assured knowing your project will be done correctly every time!

This blog article provides an overview of trusses, explores their different types, explains how they work, and discusses their benefits and limitations when designing safe and secure frames for houses.

What is a Truss and How Do Trusses Work in House Framing Design?

An image of a seismograph recording seismic activity of an earthquake. Image by adventtr from Getty Images

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Are you a structural engineer, architect, or designer looking to understand the effects of earthquakes on residential structures?

At its core, creating a safe and secure home for families requires an understanding of the environmental risks that can potentially impact its structures. This is especially true when it comes to designing a residential structure in earthquake-prone areas.  

In this blog post, we will discuss the effects of earthquakes on building design and key structural considerations for you to consider for designing safe and reliable residential homes.

## Introduction

An earthquake is a natural event that occurs when the Earth's tectonic plates move, causing the ground to shake and vibrate. Earthquakes are caused by the release of energy stored in the Earth's crust and can range in intensity from slight, barely perceptible tremors to significant, devastating events that can cause widespread damage and destruction. 

The intensity of an earthquake is usually measured using the Richter Scale. Based on their location and depth, earthquakes can also be classified into different types, such as shallow, intermediate, and deep-focus earthquakes. 

![Earthquake damage to the Alexandia Square building in Napa, California. Photo by Jim Heaphy.](https://clearcalcs-prod2-cms.s3.amazonaws.com/BLOG_seismic_analysis_2014_South_Napa_eathquake_Alexandria_Square_building_1370a1e2e8.jpg)
_Figure 1: A damaged building in downtown Napa, California, after the 6.0 magnitude earthquake on August 24th, 2014 [(Reference)
](https://commons.wikimedia.org/wiki/File:2014_South_Napa_eathquake_Alexandria_Square_building.jpg)_

In general, earthquakes can cause damage to residential buildings (Figure 1) and other types of structures, including collapse, which can result in injury or death to the occupants. 

To ensure the safety of residential structures during an earthquake, engineers and architects use [seismic load analysis](https://clearcalcs.com/blog/seismic-load-asce-7-16) methods that determine the strength and stability of the building and its components.

## Effects of Earthquakes on Residential Buildings

The movement of tectonic plates inside the lithosphere typically causes earthquakes when the rock on one side of a fault abruptly shifts relative to the rock on the other side of the fault, releasing a substantial quantity of energy in the form of seismic waves that can cause surface damage.

Earthquakes with significant ground-shaking intensities can devastate residential buildings (Figure 2) by inducing demand, causing minor to major cracks and increasing the buildings' probability of failure.

![An illustration of building sway under earthquake-induced shaking intensities. ](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_building_sway_8b3dcb92c7.png)
_Figure 2: An illustration of building sway under earthquake-induced shaking intensities._

The earthquake effects on a residential building can vary widely depending on several factors, including the earthquake's magnitude, the distance from the epicenter, and the type of soil on which a building is constructed. 

## How Do Earthquake Impact Building Structural Elements 

In general, designing buildings to withstand seismic forces requires a comprehensive understanding of the likely points of failure and the load paths that the building will be subjected to during an earthquake. 

### Connections between Structural Elements

The most critical areas of a building in terms of seismic performance are typically the connections between structural elements, such as [beams](https://clearcalcs.com/calculations/us/timberBeamASD) and [columns](https://clearcalcs.com/calculations/us/timberColumnASD). These connections must be designed to be strong and flexible, allowing the building to move without breaking. 

### Overall Structural System of the Building

Other key considerations in seismic design include the overall structural system of the building, including the type of foundation and the type of structural system used, as well as the materials used in construction. 

### Load Paths of the Building

Additionally, load paths must be carefully considered to ensure that the forces generated by an earthquake are distributed throughout the building in a way that minimizes damage.

Residential buildings that are not adequately designed and constructed to withstand seismic activity are particularly vulnerable to damage. Additionally, old structures may be more susceptible to damage than newer ones due to the lack of newer construction techniques and technologies that improve their seismic resistance. 

## Key Considerations When Designing Residential Buildings in Earthquake-Prone Areas

Under earthquakes, the building is expected to possess a range of cracks in its structural (i.e., beams, columns, bracings, and slabs) and non-structural (i.e., walls, ceilings, floors, and electrical, plumbing, and heating systems) components. Accordingly, it is important to consider separating structural and non-structural components when designing buildings to withstand seismic forces. 

The non-structural components, such as windows and curtain walls, can be particularly vulnerable to damage during an earthquake. To reduce damage, engineers should consider incorporating squishy materials, such as rubber or other flexible materials, into the design of these components. This can help absorb some of the earthquake's energy, reducing the likelihood of damage. 

Additionally, in some cases, it is important to consider incorporating movement mechanisms, such as seismic isolation and base isolation systems, into the design of the building. These systems allow the building to move in a controlled manner during an earthquake, reducing the likelihood of damage to both structural and non-structural components. 

On the other hand, while cracks in structural sections can be a concern in seismic design, as they can weaken the overall strength and integrity of the building, the point of the design is not necessarily to prevent cracks from occurring but rather to design a path for the cracks to follow that minimizes damage to other parts of the building. This is known as controlled cracking. By designing a specific path for cracks to follow, engineers can ensure that the building remains stable and that the load is distributed to minimize damage to other parts of the building.

## Conclusion

In conclusion, it is important for structural engineers, architects and designers to understand how earthquake impacts your residential structural design. Guidelines such as [ASCE 7-16](https://sp360.asce.org/PersonifyEbusiness/Merchandise/Product-Details/productId/233133882) outline the steps for determining the forces a building or structure will experience during an earthquake and evaluate the building's ability to withstand those forces. 

If you want to understand more how seismic analysis is done according to ASCE 7-16 requirements, [check out this article](https://clearcalcs.com/blog/seismic-load-asce-7-16)!


When designing a residential project, it's important to take into account the risk of an earthquake and how it could affect the building. Here we discuss some of the effects earthquakes can have and how you can plan for them.

Earthquake and Its Effects on Residential Structural Design

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When it comes to designing residential buildings, seismic load analysis is an important consideration that shouldn’t be overlooked. Structural engineers, architects, and structural designers all need to factor it into their designs in order to ensure the safety of a building during an earthquake. 

In general, earthquakes can cause damage to residential buildings and other types of structures, including collapse, which can result in injury or death to the occupants. To ensure the safety of residential structures during an earthquake, engineers and architects use seismic load analysis methods that determine the strength and stability of the building and its components.

![Earthquake damage to the Alexandia Square building in Napa, California. Photo by Jim Heaphy.](https://clearcalcs-prod2-cms.s3.amazonaws.com/BLOG_seismic_analysis_2014_South_Napa_eathquake_Alexandria_Square_building_1370a1e2e8.jpg)
_Figure 1: A damaged building in downtown Napa, California, after the 6.0 magnitude earthquake on August 24th, 2014 ([Reference](https://commons.wikimedia.org/wiki/File:2014_South_Napa_eathquake_Alexandria_Square_building.jpg))._

This article discusses the procedure for calculating seismic loads in residential buildings using the linear static approach in Chapters 11 and 12 of the ASCE 7-16.

## Seismic Load Analysis in Brief

Seismic load analysis is a procedure used to determine the forces a building or structure will experience during an earthquake and evaluate the building's ability to withstand those forces.

The procedure typically involves conducting a structural analysis of the building, including modeling the building's response to ground motion and determining the forces that will be applied to the building's various components. 

This analysis is then used to design the building's structural systems and components to resist seismic forces and ensure the building's safety and integrity during an earthquake.

The Minimum Design Loads and Associated Criteria for Buildings and Other Structures, commonly referred to as [ASCE 7](https://www.asce.org/publications-and-news/asce-7), is a standard published by the [American Society of Civil Engineers (ASCE)](https://www.asce.org/about-asce). 

The ASCE 7 standards provide guidelines for the design of structures to resist various types of loads, including wind, snow, rain, and seismic loads. The first edition of the ASCE 7 standard was published in 1988. The standard is typically updated on regular bases every three to six years, with each edition incorporating the latest research and advancements in the field of structural engineering.

Currently, the [ASCE 7-16](https://sp360.asce.org/PersonifyEbusiness/Merchandise/Product-Details/productId/233133882) is widely used in the United States and is adopted by many states and local building codes. [It is also used as a reference in other countries](https://bspace.buid.ac.ae/handle/1234/1423).

## Seismic Load Calculation Using the ASCE 7-16 Provisions

### Identifying Site Class

The procedure to perform a seismic load calculation for a residential building using the method discussed in Chapters 11 and 12 of the ASCE7-16 starts by identifying the site class (commonly done by doing a geotechnical site survey). 

The importance of correctly identifying the site class is the impact of the soil type on the seismic loads coming to the building. The mapped risk-targeted maximum considered earthquake (MCER) spectral response acceleration parameters at short periods (Ss) and at a period of one second (S1) as well as the long-period transition period (TL) based on the building location. 

These spectral parameters can be obtained from the [ASCE 7 Hazard Tool](https://asce7hazardtool.online/), using the building's longitude and latitude.

![A screenshot showing ASCE 7 online hazard tool platform used to obtain the spectral parameters ](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_asce_7_hazard_tool_bd82d56a78.png)
_Figure 2: ASCE 7 online hazard tool used to obtain the spectral parameters ([Reference](https://asce7hazardtool.online/))._

### Defining the Seismic Ground Motion Values

Once the spectral parameters for the building's site are obtained, the site coefficients (F&#8336; and F&#7525;) are defined using the data provided in Table 1.

![[BLOG]seismic-analysis-site-coefficients.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_site_coefficients_7e5a676e31.png)
_Table 1: Site coefficients at short and one-second periods_

Thereafter, the design response spectrum is developed using Eqs. 1 to 4 as well as Figure 3. 

![[BLOG]seismic-analysis-design-response-spectrum.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_design_response_spectrum_dc7ca7eb29.png)

where S&#8344;&#8347; and S&#8344;&#8321; are the MCER, 5% damped, spectral response acceleration parameter at a short period and period of 1s, respectively; SDS and SD1 are the design, 5% damped, spectral response acceleration parameter at a short period and period of 1s, respectively.

![Design response spectrum defined in the ASCE 7-16](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_design_response_spectrum_chart_698b50cff8.png)
_Figure 3: Design response spectrum defined in the ASCE 7-16 ([Reference](https://sp360.asce.org/PersonifyEbusiness/Merchandise/Product-Details/productId/23313388))._

### Obtaining the Seismic Force Resisting System (SFRS) Properties

Once the design spectrum is established, the risk category, response modification coefficient (R) based on the type of seismic resisting system and the material used, importance factor (Ie), and approximate period parameters Ct and x are obtained from Tables 2, 3, 4, and 5, respectively. 

![Risk category of buildings and other structures under various load types](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_risk_category_table_219a6d3ba0.png)
_Table  2: Risk category of buildings and other structures under various load type_

![An example of the design coefficients and factors for various seismic force-resisting systems ](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_design_coefficient_factors_table_76e6905cd6.png)
_Table  3: An example of the design coefficients and factors for various seismic force-resisting systems_

![Importance factors for various load types ](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_importance_factors_42bd7234e7.png)
_Table  4: Importance factor for various load types_

![Values of approximate period parameters Ct and x](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_approximate_period_parameters_1ad3552239.png)
_Table  5: Values of approximate period parameters Ct and x_

### Calculating the Effective Seismic Weight on the Building

Once the parameters are obtained and set, the effective seismic weight of each story in the residential building is calculated based on the self-weight of the structural and non-structural elements and the partial contribution of the live load in the building. 

Moreover, the structure's natural period (T) in the direction of concern is computed according to the method explained in section 12.8.2 of the ASCE 7-16. Thereafter, the seismic response coefficient is calculated using Eq. 5 and checked against the conditions in Eqs. 6, 7, and 8. 

![Seismic response coefficient Cs formula ](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_seismic_response_coeffecients_formula_84daa96a1c.png)

The value of Cs shall not exceed, for T ≤ Tʟ:

![[BLOG]seismic-analysis-base-shear-equation-6a.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_base_shear_equation_6a_9689ed7bd1.png)

for T > Tʟ:

![[BLOG]seismic-analysis-base-shear-equation-6b.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_base_shear_equation_6b_ce2deb256d.png)

The value of Cs shall not be less than

![The seismic coefficient response value against SDS and importance factor](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_seismic_response_coeffecients_equation_7_c24d08e1ba.png)

In addition, for structures located where S1 is equal to or greater than 0.6g, the value of Cs shall not be less than
![Seismic response coefficient for structures located where S1 is equal to or greater than 0.6g](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_seismic_response_coeffecients_equation_8_14f023f56e.png)

### Calculating Seismic Base Shear

Finally, the seismic base shear of the structure in the direction of concern is calculated using Eq. 9 and distributed to each story using Eq. 10.  

![The formula for seismic base shear acting on the base of the building due to lateral earthquake loads. ](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_base_shear_equation_9_83efbfa2d0.png)

where W is the effective seismic weight of the structure

![Lateral force formula](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_base_shear_equation_10_7ce6ff10fb.png)

where  C_vx is the vertical distribution factor calculated as 

![Cvx vertical distribution factor formula](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_seismic_analysis_base_shear_equation_11_84d5024d4e.png)

w_x and w_i are the portion of the total effective seismic weight of the structure located or assigned to levels x and i, respectively; h_x and h_i are the height from the base to levels x and I, respectively; k is an exponent related to the structure's period where k = 1 for a period of 0.5s or less, k = 2 for a period of 2.5s or more, and k is linearly interpolated between 1 and 2 for periods between 0.5 and 2.5s.

## Conclusion

In order to comply with ASCE 7-16 requirements for analyzing seismic loads in residential buildings, engineers must follow the procedure outlined in Chapters 11 and 12. To find out how ClearCalcs integrates these calculations for seismic load analysis, check out our [Seismic Analysis Calculator to ASCE 7-16](https://clearcalcs.com/calculations/us/seismicAnalysisUS). 

#### Ready to start calculating in ClearCalcs? 

[You can use the account for 14 days for free](https://clearcalcs.com/signup), with no commitment required. Need ClearCalcs for a one-off project? Subscribe to our month-to-month plan and cancel anytime, no questions asked.

#### References
- Aksoylu, C., Mobark, A., Hakan Arslan, M., & Hakkı Erkan, İ. (2020). A comparative study on ASCE 7-16, TBEC-2018 and TEC-2007 for reinforced concrete buildings. Revista de la Construcción, 19(2), 282-305.
- American Society of Civil Engineers. (2017). Minimum design loads and associated criteria for buildings and other structures. American Society of Civil Engineers.
- AL-OBAIDI, A. L. I. (2018). Comparison between the American code ASCE7-16 and the Australian code AS1170. 4 against the seismic design 
- Fajfar, P. (2018). Analysis in seismic provisions for buildings: past, present and future. In European Conference on Earthquake Engineering Thessaloniki, Greece (pp. 1-49). Springer, Cham.


This article discusses the procedure for calculating seismic loads in residential buildings using the linear static approach in Chapters 11 and 12 of the ASCE 7-16.

Seismic Load Analysis for Residential Buildings to ASCE 7-16 Requirements

An image showing two hands over a drawing of structural plan.

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As a structural engineer in California, staying updated on the latest building codes is vital to ensure the safety and integrity of the structures your design. The California Building Code 2022 is the most recent update to the state’s building regulations, and it includes several significant changes and additions that structural engineers need to know.

So whether you’re just beginning your career or are a seasoned pro, read on for some of the most important things you need to know about the newest version of California’s building code.
# Overview of the California Building Code

The [California Building Code](https://www.dgs.ca.gov/BSC/Codes) (CBC) is the set of regulations governing the design, construction, alteration, and maintenance of buildings and structures in the U.S. state of California. Part of Title 24 of the California Code of Regulations (CCR), the CBC falls under the jurisdiction of the [California Building Standards Commission](https://www.dgs.ca.gov/BSC) (CBSC). 

The CBC includes multiple amendments by various state agencies, ranging from the State Fire Marshall to the Department of Health Care Access and Information (referred to as the Office of Statewide Health Planning and Development - OSHPD in the code). **This article will principally focus on designs for light commercial and residential buildings.**

## Local Jurisdictions and Their Effects on the CBC

In addition to the CBC, your local city or county may also file its local amendments to the CBC (known as Local Building Codes or Ordinances) with the CBSC. The amendments may be more or less restrictive in nature depending on the area’s climatic, geographical, or topographical conditions. You can find [relevant ordinances for your local city or county](https://www.dgs.ca.gov/BSC/Codes/2022-ordinances) on the CBSC website and contact them to get a copy of filed ordinances of the city or county of your interest.

### Example - City of Pleasanton

Let’s say we’re designing a building in Pleasanton, California. Looking through the CBSC database, we’ll find that the city has filed Ordinance No. 2241 to their local amendments in conjunction with the adoption of the CBC 2022, where the [Pleasanton Building Code Sections 20.08.080](https://library.qcode.us/lib/pleasanton_ca/pub/municipal_code/item/title_20-chapter_20_08-20_08_080) completely replaces the [CBC Section 1905.1.7 in Chapter 19 Concrete](https://codes.iccsafe.org/content/CABC2022P1/chapter-19-concrete#CABC2022P1_Ch19_Sec1905) with fewer exceptions for allowable plain concrete in structures assigned to seismic design category C, D, E or F, among other things.

![pleasanton-2241.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/pleasanton_2241_818650e629.png)
_Image: [Pleasanton Building Code Sections 20.08.080](https://library.qcode.us/lib/pleasanton_ca/pub/municipal_code/item/title_20-chapter_20_08-20_08_080)_

# California Building Code 2022

The California Building Code (CBC) is revised every three years. The most recent revision was published in 2022, and the next will likely be the 2025 version. The CBC 2022 is based on the [2021 International Building Code.](https://codes.iccsafe.org/content/IBC2021P2)

The 2022 edition was published on July 1, 2022, and went into effect across the state on January 1, 2023.

## Structural Design

Some of the [key provisions related to structural design](https://codes.iccsafe.org/s/CABC2022P1/chapter-16-a-structural-design/CABC2022P1-Ch16A-Sec1605A) in CBC 2022 include:
- Most load calculations and combinations in buildings and other structures are now delegated to the specifications of [ASCE/SEI 7, Minimum Design Loads and Associated Criteria for Buildings and Other Structures](https://www.asce.org/publications-and-news/asce-7).
- Structural deliverables to be submitted to permit reviewers must now include [design wind pressures and their applicable zones with dimensions](https://codes.iccsafe.org/content/CABC2022P1/chapter-16-structural-design#CABC2022P1_Ch16_Sec1603.1) as part of the wind loads data, compared to only needing to provide only wind pressures in the previous revision.
- CBC 2022 now includes further requirements for special inspections of, among others, [mass timber](https://codes.iccsafe.org/content/CABC2022P1/chapter-17-special-inspections-and-tests#CABC2022P1_Ch17_Sec1705.5.3) and [steel storage racks](https://codes.iccsafe.org/content/CABC2022P1/chapter-17-special-inspections-and-tests#CABC2022P1_Ch17_Sec1705.13.7). 
- New r[equirement for structural observations by a professional engineer for structures](https://codes.iccsafe.org/content/CABC2022P1/chapter-17-special-inspections-and-tests#text-id-26748291) that are classified as Risk Category III and IV, or that are assigned to Seismic Design Category E and have more than two stories above the grade plane. 

## Seismic Loads 

One of the key changes in the seismic load requirements by the CBC 2022 is the adoption of  [Supplements 2](https://ascelibrary.org/doi/10.1061/9780784414248.sup2) and [3](https://ascelibrary.org/doi/abs/10.1061/9780784414248.sup3) of ASCE 7-16.

In the past, you might have been concerned about when a site-specific analysis is required for your projects, especially when dealing with structures on Site Class D, which is the default site class in most projects. 

Given that site-specific ground motion procedures can be complicated and expensive, the adoption of Supplement 3 of ASCE 7-16 in the CBC 2022 clarifies the requirements to bypass the site-specific analysis. These can be avoided by:
- Increasing the 1s acceleration (SM1) by 50% for Site Class D with Ss > 0.2
- Always using short-period acceleration (SDS) for Site Class E with Ss > 0.2 or S1 > 1.0

Additional changes in the CBC 2022 are related to more complex seismic analysis, which you can refer to directly in Supplements 2 and 3 of ASCE 7-16, which are [available for free online](https://ascelibrary.org/doi/book/10.1061/9780784414248).

## Foundations Design 

Where residential projects take place in frost-prone areas, the CBC 2022 now requires [frost protection](https://codes.iccsafe.org/content/CABC2022P1/chapter-18-soils-and-foundations#CABC2022P1_Ch18_Sec1809.5) for all exits with outward-swinging doors to avoid any heaving to occur that might obstruct the opening of the exit doors.

![Image showing a door warning sign due to frost heave effects.](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/frose_heave_idighardware_7ae8a79f76.jpg)
_Image: [Example of the Effect of Frost Heave](https://idighardware.com/2015/02/ww-frost-heaves/)_

Additionally, if you are designing deep foundations, the CBC 2022 includes requirements to design: 
- [Precast concrete piles and pile caps in accordance with ACI 318](https://codes.iccsafe.org/content/CABC2022P1/chapter-18-soils-and-foundations#CABC2022P1_Ch18_Sec1810.3.8) (with some exceptions) 
- [Structural steel H-piles](https://codes.iccsafe.org/content/CABC2022P1/chapter-18-soils-and-foundations#CABC2022P1_Ch18_Sec1810.3.5.3.1) to the stricter requirements of AISC 341 for structures assigned to Seismic Design Category D, E, or F
- Some other clarifications (e.g., [helical pile formulas](https://codes.iccsafe.org/content/CABC2022P1/chapter-18-soils-and-foundations#CABC2022P1_Ch18_Sec1810.3.3.1.9)).

## Update to Wood Design Requirements According to AWC SDPWS 2021

[The American Wood Council's (AWC) Special Design Provisions for Wind and Seismic (SDPWS)](https://awc.org/publications/2021-sdpws/) has been updated to the latest 2021 edition with the CBC 2022, providing detailed governing criteria for engineered wood systems, members, and connections in lateral force-resisting systems such as wood shear walls and diaphragms. 

Among other changes, the SDPWS 2021 has combined wind and seismic design values for diaphragms and shear walls into a single value, which is modified by safety factors appropriate for each condition ([SDPWS 2021, 4.1.4 and Table 4.2 & 4.3](https://awc.org/pdf-viewer/?idp=4070&idf=4)). These changes have led to reductions in the shear strength for wood panel (LRFD) or gypsum board and plaster (ASD) by 11% and 30%, respectively. 

In addition, there are now stricter rules for multi-story buildings with Seismic Design Category D, E, or F ([SDPWS 2021, 4.1.8](https://awc.org/pdf-viewer/?idp=4070&idf=4)), as well as new provisions for construction with [cross-laminated timber (CLT)](https://codes.iccsafe.org/content/CABC2022P1/chapter-6-types-of-construction#CABC2022P1_Ch06_Sec602.4.4.2) in exterior walls ([SDPWS 2021, 4.5 and 4.6](https://awc.org/pdf-viewer/?idp=4070&idf=4)).

## Concrete Design Updated to ACI 318-19

The California Building Code 2022 (CBC 2022) has brought significant development to concrete design requirements. Instead of referring to the American Concrete Institute's ACI 318-14, it now uses the newly updated standard for structural concrete: [ACI 318-19](https://www.concrete.org/store/productdetail.aspx?ItemID=318U19&Language=English&Units=US_Units).

In particular, ACI 318-19 now allows more applications using [high-strength reinforcements up to 100 ksi](https://www.concrete.org/Portals/0/Files/PDF/CI4108Moehle.pdf?Format=ONLINE_LEARNING) in your designs, opening up new possibilities for those working with this material. 

### Concrete Shear Capacity

Additionally, the shear strength calculation has been reworked, too, resulting in a much lower shear capacity for concrete structures that don’t have transverse reinforcement, such as stirrups.

Compared to the previous edition, the [ACI 318-19 now introduces a size effect factor (λs) and considers reinforcement ratio (ρ) in its shear strength Vc calculation](https://www.concrete.org/Portals/0/Files/PDF/CI4108Moehle.pdf?Format=ONLINE_LEARNING).

Let’s take a look at the differences in the shear strength formula:

#### Shear Resistance Vc According to ACI 318-14
Vc=2λ√(fc′)bwd

#### Shear Resistance Vc According to ACI 318-19
Vc=8λs λ(ρw)1/3 √fc′ bwd

As an example, for a lightly-reinforced footing (ρw = 0.002 and size factor λs = 1.0 per Cl 13.2.6.2), we would obtain a factor of ~1.0 instead of 2.0 for the shear strength, resulting in a 50% reduction in shear capacity.

This formula modification may result in significantly thicker footings, structural slabs, and walls.

### Concrete Shear Size Factor

With the new set of equations for shear strength, ACI 318-19 introduces the [factor λs, the "Size Effect" for](https://www.concrete.org/Portals/0/Files/PDF/CI4108Moehle.pdf?Format=ONLINE_LEARNING) sections with no minimum shear reinforcement. 

This will affect beams, slabs, and walls with a depth of 10 inches or more. For instance, a 24-inch thick slab will have its shear capacity reduced by 25% with the size effect factor considered. 

Isolated and combined footing designs are not affected by the size effect factor.

# Using Computer Programs to Support Analysis Under the Latest Building Code 2022

Managing the transition from the CBC 2019 to the CBC 2022 can be challenging. As a structural engineer, you’re always looking for ways to use technology to streamline your work. 

Luckily, a few computer programs come in handy when following the latest California Building Code 2022.

Firstly, structural engineering software like ClearCalcs now enables you to define the California Building Code 2022 as the governing code of your project’s load combinations and design criteria in [Project Defaults](https://support.clearcalcs.com/article/177-project-defaults-us). This means the set of default/preset values for the code in question will carry through to every new calculation you create in ClearCalcs.  

![Screenshot of ClearCalcs software showing project defaults section with California Building Code as the governing design criteria](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/cbc2022_project_Defaults_c061fc36c3.png)
_Image: [ClearCalcs Project Default Section](https://support.clearcalcs.com/article/177-project-defaults-us)_

You can use wind load or seismic analysis calculators to meet the requirements of ASCE 7-16, which is referenced heavily in CBC 2022.

The [ClearCalcs Wind Load Calculator to ASCE 7](https://clearcalcs.com/calculations/us/loadsWindCnCASCE7-16) is a tool that allows you to perform in-depth wind analysis, and the [Seismic Analysis Calculator to ASCE 7](https://clearcalcs.com/calculations/us/seismicAnalysisUS) from ClearCalcs is a user-friendly tool for performing seismic analysis according to the ASCE 7 code.

Finally, the ClearCalcs Concrete Beam Calculator is now updated to the latest ACI 318-19 edition, and other calculations will be updated in the next few weeks. 

# Conclusion

There you go! We hope this guide has set you up to align with the California Building Code 2022.

To recap, the California Building Code 2022 incorporates some key changes to structural design requirements, including the complete adoption of ASCE 7 and Supplement 2 and 3 for seismic analysis requirements. 

The most significant change to note is the update to the concrete design requirement with the ACI 318-19, which might affect the shear capacity of your concrete structures with the new reworked shear capacity formula.

So, whether designing a new building or retrofitting an old one, make sure you factor in these California Building Code 2022 requirements. If you are [designing a residential home](https://clearcalcs.com/use-case/residential-design) in California, check out ClearCalcs library of calculators to use from roof to foundation with presets for wood, steel, or concrete.

[Contact us](https://clearcalcs.com/use-case/residential-design) to learn more about how our Wind Load and Seismic Analysis Calculators can help, or [try ClearCalcs for free](https://clearcalcs.com/signup).

Learn what a structural engineer needs to know about the California Building Code 2022, from building regulations to key requirements. Get up to speed today!

Everything a Structural Engineer Needs to Know About the Latest California Building Code 2022

ClearCalcs co-founders Chris Borzillo and Steven Robinson standing next to each other at ClearCalcs office.

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Australian engineering and structural design startup, ClearCalcs, has secured an additional AUD2.5 million in funding, taking its total pre-series capital to $5 million. 

Led by existing investors, [EVP](https://www.evp.com.au/) and [Shearwater Capital](https://www.shearwater.co/), the investment comes as demand for the business' unique eng-tech software, which is helping to address the global need for more sustainable and efficiently built housing, booms.

Since its most recent funding round of $1.65m in November 2021, ClearCalcs has more than doubled its revenue and grown the team eight to 23 employees. The business has also opened a North American office, where approximately 70% of its users are based.

## Building strategic partnerships to serve users better

The new capital will be used to bring to life the next stage of the startup’s growth roadmap. This includes reaching more potential users through strategic partnerships, expanding the software’s offerings and materials, and further bolstering its talent pool. The most recent hire of note being Mustafa Gürsoy, who joined in September as Head of Growth from fast growing North American startup MaxSold. 

ClearCalcs houses a comprehensive library of mission critical calculation tools that enable engineers, architects and building designers to better determine the structural requirements for their projects. As a result, customers are able to design and build safe, compliant structures with speed, accuracy and flexibility. 

It has become the go-to software solution for its industry, especially as housing affordability globally reaches crisis point. 

Headquartered in Melbourne and launched in 2017 by co-founders Chris Borzillo and Steven Robinson, the company now has an established presence in the US, Canada, Europe, Australia, and New Zealand. 

## Catalyzing innovation in the least digitized industry

Speaking of the news, Borzillo said, “At ClearCalcs, we’re servicing a market that is desperate for change and better support, but with incredibly complex requirements. While the eng-tech field is niche, we understand the intimate specifics of our community. By leaning into this, we’ve been able to build a business that is swelling in potential and uptake. 

“Our software gives those in the design engineering space the tools they need to do their job at speed and with incredible accuracy. As a result, they can trial new and different materials that would previously have been too time consuming to consider. This is not only reducing the time it takes for housing to move from concept to reality, but also changing how engineering is approached.” 

“We’re enabling creativity and consideration in a space that is under immense pressure. Despite being a fundamental human need, housing worldover is in short supply. This is the result of material and trade shortages but also growing populations and changing needs and expectations around living conditions.” 

“Our goal is to empower ambitious and sustainably focused engineers to solve these issues, creating better outcomes for their own businesses but also the people they serve and ultimately the environment.”

## Building a global company with community as its north star
Mark Velik, Investment Manager at EVP said, “Every step along the way, Chris and Steve have achieved exactly what they said they were going to, first and foremost with their rapid revenue growth. Their vision for ClearCalcs and the problems it can solve is unparalleled, but it’s not just this that has us coming back to reinvest. It’s the tenacity, gumption and dedication they bring to their community that stands out. They are well on their way to building a business of significant scale, with double the enthusiasm and passion of most. 

“They are also steadfast in creating a culture that enables their team to thrive which is much more advanced than most businesses of their size. We believe deeply in all they’ve set out to achieve and look forward to supporting them as they continue to grow.”

Zac Zavos, Co-Founder & Managing Partner at Shearwater Capital said, “Chris and Steve have built a business with enormous global scale and potential. Year on year we're seeing impressive growth and this is due to the high quality product the team has developed combined with the strong engineering culture within the business.”

Borzillo added, “From day one we set out to grow a values based business. Both Steve and I are incredibly humbled to be at the helm of a startup that is not only improving the work of our community, but ultimately the lives of hundreds of thousands of people too who live in the projects our software helps create. While our tech is already in the hands of thousands of users, we’re only just scratching the surface of our potential and are incredibly thankful to have the ongoing support of our original investors.”

Australian engineering and structural design startup, ClearCalcs, has secured an additional AUD2.5 million in funding, taking its total pre-series capital to $5 million. 


ClearCalcs Engineers $2.5m Funding Top Up as Its Global Growth Swells

A photo showing an architect working on a draft with a pencil and rule

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As building professionals, you may be required to have a basic understanding of structural technology to perform structural design analysis and calculations for your projects. 

Unfortunately, most structural design software isn't designed for residential architects -- which is why, as an architect, you've likely faced these issues:
- Most structural engineering software is too elaborate for architects to use
- They are expensive, as they are loaded with different features you're never likely to use
- You often need to dedicate many hours to understand or become familiar with the software

Additionally, while there is plenty of simpler software available, you often need to use 3+ tools to help with designing different materials or to spend a long time manually to make your entire design work.

In this article, we will be walking you through how to easily set up your structural calculation for common structures in residential houses in ClearCalcs within minutes.

_Looking to try structural design software right away? You can open one with ClearCalcs in under 2 minutes and [sign up for our free 14-day trial.](https://clearcalcs.com/signup)_

Want to find out the exact steps you'll need to go through in order to create your structural calculation? Keep reading!

## What do you need to get started with structural design

Here is what you need to get started with your structural design calculations. 

### Your drawing plan
Generally, the structural design process begins with the design blueprint of the residential house being built. This will enable you to identify the relevant members involved in the construction and select the most suitable materials that can safely uphold the structure. 

![[BLOG] residential-architect-plan.jpg](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_residential_architect_plan_707fb60e09.jpg)

The most common members you can design in ClearCalcs:
- wood beams like roof headers, floor joists, rafters, those for load bearing wall removal, etc.
- wood columns like posts for decks, stud walls, or even lally columns
- footings such as spread footing or pad footing, and pier footing for a deck

### Your project setup
In ClearCalcs, your set of calculations (like beams, columns, and footings belonging to the same structure such as a residential house) is grouped in a project tied by the project name, job number, client name, address, and building standards. 

![[BLOG] residential-architect-project-set-up.jpg](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_residential_architect_project_set_up_319659822e.jpg)

To create your project:

**1. Identify your building code**
When you sign up to ClearCalcs, you will be automatically assigned a default building standard based on your selected country of origin. 

For example, if you're an architect from the United States, you will be assigned the US building standard, and your calculation will default to the International Building Code (IBC) 2018. 

You can change the building standard applicable to your project once you have identified the specific member you want to calculate for.

**2. Input your address**
This feature currently only locates the project in the Google Map. Future integration will include automatic calculation of wind load specific to your project.

**3. Set your preferred sections (optional)**
If you already have specific material (wood or steel), manufacturer types, or species you will be working with for your project due to clients' requirements, you can [set your preferred sections](https://support.clearcalcs.com/article/56-how-to-use-preferred-sections-and-autosize) so you can save time to quickly access the list of your favorite sections in your calculation.

## How to set up your first structural calculation 

Now that you're ready with your residential layout and project information. Here's how to get started with your first calculation. 

**1. Identify the structure you're designing**
Let's say you are designing a residential deck comprising four main structural elements of deck joist, deck beam, deck post, and pier footing. You can start with your calculation by [adding a new calculation](https://support.clearcalcs.com/article/132-creating-new-calculations) to your project and choosing[ Wood Beam to ASD or LRFD Requirements: Wood Joist Calculator](https://clearcalcs.com/calculations/us/timberBeamASD). 

![[BLOG] residential-architect-wood-joist.jpg](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_residential_architect_wood_joist_986e0225be.jpg)

_Note: Not sure which to use? Based on our user data, it's most common to use ASD for Wood and LRFD for Steel._

**2. Input the key properties of your member**
This generally includes the key geometry (eg. beam plan length) and the support conditions (fixed, pinned, or roller support).

_Note: Need more info about the different support types? Read our support guide on [how to enter beam supports in ClearCalcs](https://support.clearcalcs.com/article/148-how-to-enter-beam-supports-imperial-units)._

![[BLOG] residential-architect-key-inputs.jpg](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_residential_architect_key_inputs_4cd574139b.jpg)

**3. Input loads**
Easily enter loads to be factored and analyzed on your calculation. In ClearCalcs, you can add different loading types in combination to your member. 

![[BLOG] residential-architect-load-input.jpg](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_residential_architect_load_input_16be0a4898.jpg)

**4. Select your material type**
Once you've finished entering the geometry and loads of the calculation you want to analyze, you can evaluate if your calculation passes satisfactorily by selecting your desired type members in any of our materials libraries.

![[GIF] traffic lights.gif](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/GIF_traffic_lights_dfd73d1754.gif)

The Member Selector will automatically summarize your governing checks to make sure your calculation passes in green or yellow (red means fail)! 

## What else can you do with ClearCalcs?
What else can you do in ClearCalcs once you have created a calculation? Here are a few things:

### Link the reactions of your loads with other load-bearing members 
The problem with manually doing your design calculations is that anytime you work with two or more load-bearing members, you need to update your calculations every time you make changes upstream or downstream. 

With ClearCalcs, you can [easily link reactions between beams, columns, and foundations](https://support.clearcalcs.com/article/24-linking-reactions-between-beams-and-columns-load-path-tracking) as point loads or line loads where applicable. And the loads will be dynamically tracked through the structure in the same project. 

![Load linking between beams and columns](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/load_linking_98297dfb69.jpg)

If the top calculator's reactions change, the loads being inherited onto the lower calculator will update automatically. No need to copy and paste reactions between calculations! 

### Export your calculation for submittals to permit reviewers
ClearCalcs [export feature](https://support.clearcalcs.com/article/23-exporting-calculations-and-member-schedule) enables you to either export the entire project or select a specific calculation to export as a summary. 

![[BLOG] printout-example.jpg](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_printout_example_c5f754db1c.jpg)

The report automatically includes the governing checks of each calculation as well as clear assumptions such as the design code, references, etc.

_Ready to start calculating in ClearCalcs? [You can use the account for 14 days for free](https://clearcalcs.com/signup), with no commitment required. Need ClearCalcs for a one-off project? Subscribe to our month-to-month plan and cancel anytime, no questions asked._



How to easily set up your structural calculation for common residential structures with structural design software like ClearCalcs.

Structural Design for Residential Architects: How to Get Started

Image showing retaining wall diagram with text How to Design Sleeper Retaining Wall

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In residential house construction, a retaining wall is required when there is a significant slope on the property that is being built on, and support is needed to hold back a sloping section of soil.

Primarily, the function of a retaining wall is to resist the weight of soil pushing against it, and the design of it needs to ensure deep enough foundations and strong enough structural components. One of the most challenging aspects of designing a retaining wall is accurately understanding [the impact of the soil properties on the retaining wall calculations](https://support.clearcalcs.com/article/200-how-to-design-a-sleeper-retaining-wall-in-cohesive-soil).

Our Head of Engineering R&D, Brooks Smith, shared how you can use ClearCalcs to solve your [sleeper retaining wall design calculations](https://clearcalcs.com/calculations/au/retainingWallSleeperCohesive). We showed you how to keep your parameters as simple as possible while ensuring your calculations are accurate, make conservative assumptions to make your calculations work, and how you can easily link reactions between the sleepers and the retaining wall.

[Watch the full webinar recording](https://www2.clearcalcs.com/videos/retaining-wall-au).

How to Design Sleeper Retaining Wall to Australian Standards 4678-2002 & 2159-2009 with ClearCalcs

Sleeper retaining wall design to AS 4678-2002 & 2159-2009

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In typical house construction where standard roof framing is involved, the ceiling is constructed using a combination of wood joists and beams that run across the length and width of the ceiling. The 2015 International Residential Code (IRC) currently regulates the design and construction of roof and ceiling systems to ensure they are designed correctly to provide adequate support required by the imposed loads.

While the conventional frame-style ceilings typically follow a standard framing process with few surprises, what happens when your design isn’t standard or prescriptive?

Our resident structural design expert shared how you can feel more confident when designing custom roof and ceiling designs in this webinar. You'll learn how to use ClearCalcs to provide supporting design calculations for your permit review and approval process. We also shared tips and tricks on keeping your design decisions in-house, making design calculations the easiest part of your job.

[Watch the full webinar recording](https://www2.clearcalcs.com/videos/roof-ceiling-construction-webinar).

Learn more about how you can feel more confident when designing custom roof and ceiling designs and how to use ClearCalcs to provide supporting design calculations for your permit review and approval process.

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